H11E-0801
Hydrology, Water Scarcity and Market Economics
Research scientists claim to have documented a six-fold increase in water use in the United States during the last century. It is interesting to note that the population of the United States has hardly doubled during the last century. While this indicates higher living standards, it also emphasizes an urgent need for establishing a strong, sound, sensible and sustainable management program for utilizing the available water supplies efficiently. Dr. Sandra Postel directs the independent Global Water Policy Project, as well as the Center for the Environment at Mount Holyoke College in South Hadley, Massachusetts. Author of the 1998 book, Last Oasis: Facing Water Scarcity, Dr. Postel predicts big water availability problems as populations of so-called "water-stressed" countries jump perhaps six fold over the next 30 years. The United Nations declared the years 2005 – 2015 as the "Water for Life" decade. It is also interesting and important to observe that the Oil – Rich Middle – East suffers from water scarcity to the maximum extent. It is also recognized that almost three-quarters of the globe is covered with water. Regardless, this is salt-water and there is very limited supply of freshwater to meet the needs of exploding global population. In excess of 10,000 desalination plants operate around the world in more than a hundred countries, but such a process is expensive and may seem prohibitive for developing countries with limited resources. Farmers can cut water usage by adopting the method known as drip irrigation which is known to be highly efficient. Drip Irrigation was pioneered by Israel and the Israeli farmers documented their efficiency by reducing the water used for irrigation by more than 30 percent. Unfortunately the rest of the world has failed to follow the lead set by this Great Jewish Nation. Worldwide, hardly 1percent of irrigated land utilizes efficient drip irrigation techniques. The problem lies in the fact that water is considered to be a free natural commodity. Applying the principles of Market Economics to this problem may promote the transfer of a monetary value to freshwater. In this presentation the author examines the possibility of applying principles of Market Economics to the problem in question. It is important to recognize that water is essential for the survival of all life on earth. Many water-rich states have thought of water conservation as an art that is practiced mainly in the arid states. But one has to recite the famous quote: "You will never miss water till the well runs dry." Quantity deficiency experienced by groundwater supplies are affecting many communities and furthermore federal regulations pertaining to the quality of potable or drinking water have become more stringent. It is also important to observe the fact that one can protect the environment by practicing water efficiency procedures and saving valuable water resources. It may seem that there may be heavy investment involved, however, in reality these do have a short payback period. References: Postel, Sandra L. The Last Oasis: Facing Water Scarcity. New York: W. W. Norton and Company. 1997. Worldwatch Institute, 1776 Massachusetts Ave., NW, Washington, DC 20036, Phone: 202-452-1999; FAX: 202-296-7365, wwpub@igc.apc.org. MRI Water Conservation Technical Bulletin 1, Water Conservation Best Management Practices General Practices and References; New England Interstate Water Pollution Control Commission, Wilmington, MA; 1996. Vickers, Amy; Handbook of Water Use and Conservation; WaterPlow Press, Amherst, MA; 2001; pp 2-9, 276.
H11E-0802
Modelling global water stress at the monthly time-scale
It is estimated that currently over one billion people have problems obtaining access to sufficient freshwater resources, while due to population growth and climate change the number of people affected by water scarcity and water stress will rise to four billion by 2050 (UNEP, 1999). To assess current water stress and it development under different socio-ecomomic and climate scenario's Global Hydrological Models (GHMs) are important tools. Until now, GHM-analyses calculating water demand and water availability have been performed on yearly totals only. However, it can be expected that availability of water is often out of phase with water demand and that actual water stress may be underestimated using yearly totals. Also, yearly budgets cannot shed light on the persistence and recurrence time of water stress. In this paper we present an analysis of global water stress based on monthly data of water availability and water demand. Here, severe water stress is defined to occur in case local water demand exceeds 40% of the local water availability A 40-year time series of water availibility is obtained by the GHM PCR-GLOBWB forced with CRU meteorological data downscaled to daily time steps using the ERA40 re-analysis dataset. Thus, apart from representing a within-year regime, the water availability analyses also consider between-year climate variability. Availability calculations contain both local precipitation surplus (precipitation minus evaporation), but also upstream river discharge, water in reservoirs, groundwater abstraction as well as green water (soil water used by irrigated crops). Water demand is calculated on a monthly basis for the year 2000, while these monthly values are taken constant over the years. It consists of water demand for agriculture (both rainfed as well as irrigated and lifestock), industry and domestic water use. Domestic water demand as well as the recycling fraction of industrial and domestic water demand for each country are related to its development stage. In our calculations, water demand interacts with water availability in two ways. Irrigation water demand depends on the transpiration deficit as calculated with PCR-GLOBWB, while water availability from upstream river discharge is corrected for upstream blue water demand. Results show that calculations of global water stress based on montly analyses result in more regions that experience severe water stress. This indeed suggests that analyses based on yearly average water availability and demand underestimate global water stress. Analyses of water stress persistence and recurrence time reveal areas where prolonged periods of water stress occur (e.g. North India) as well as areas where the average water stress is low, but ocassionaly short periods of severe water stress are possible (e.g. South-East England).
H11E-0803
Seasonal and Annual Variability of Hydrologic Fluxes in Post-fire Watersheds in Southern California
Fire dramatically alters watershed characteristics and in situ processes. Vegetation loss and acute changes in soil properties significantly change land-atmosphere interactions and overall water balance within a burned system. A significant number of studies have studied post-fire storm response, debris flows, sediment transport, and water quality impacts. However, fewer studies have investigated the spatial and temporal patterns of vegetation response (evaporative flux) and the corresponding impacts on flow regimes, especially in semi-arid regions. The current study is undertaken to further understanding of short- and long-term hydrologic response to fire and offer insight on vegetation response and evaporative processes in post-fire chaparral systems. Initial investigation centers on two watersheds (City Creek and Devil Canyon) burned during the 2003 Old Fire in San Bernardino in southern California. Climate and discharge data are used to evaluate seasonal and annual variability and provide information on post-fire fluxes. Additionally, we utilize an extensive array of MODIS satellite products to observe land surface and vegetation recovery, including a recently developed MODIS-based potential evapotranspiration product. Initial results indicate increased discharge up to four years in both systems, with apparent elevated dry season flow for much of the post-fire period. Vegetation response is heavily influenced by seasonal precipitation patterns, but does not appear to be back to pre-fire evaporative conditions during this same period. Studying pre and post-fire hydrologic variability and linkages to regional climate patterns will help to further our understanding of recovery processes and, ultimately, assist in flood control and water resource management activities.
H11E-0804
Integrating Soft Data into Hydrologic Modeling to Improve Post-fire Parameter Estimates
A significant problem with post-fire streamflow prediction is the limited availability of data for parameter estimation and for independent validation of model performance. The goal of the current study is to evaluate a range of optimization techniques which allow integration of alternative soft-data data into a hydrologic modeling and prediction framework and improve post-fire simulations. This project utilizes the Sacramento Soil Moisture Accounting Model (SAC-SMA), the National Weather Service operational conceptual rainfall- runoff model and incorporates both discharge and geochemical data to estimate model parameters. The analysis is undertaken in a watershed which has undergone an extensive land cover change (fire) and for which both pre- and post-fire geochemical and streamflow data are available. We utilize the Shuffled Complex Evolution Metropolis (SCEM) and the Generalized Likelihood Uncertainty Estimation (GLUE) algorithms coupled to the SACSMA and integrate estimates of geochemically-derived flow components. Success is determined not only by the accurate prediction of total discharge, but also by the prediction of flow from contributing sources (i.e. overland, lateral and baseflow components). The coupled SCEM-SACSMA, using only discharge as a criterion, shows reasonable simulation of total runoff and various flow components under pre-fire conditions. Post-fire model simulations show less accurate simulation of total discharge and unrealistic representation of watershed behavior. Pre-fire model runs using the coupled GLUE-SACSMA show reasonable performance integrating total discharge as the threshold criteria; whereas the post fire model run returned empty parameter sets (no sets met threshold criteria). Predictions using the GLUE- SACSMA and derived flow components showed significant improvement, narrowing the uncertainty bounds in total discharge as well as all observed flow components.
H11E-0805
Patterns of Streamflow Response to Urbanization in the Northeast U.S. Megalopolis
Urbanization is widely believed to have the following effects on streamflow: (1) increasing storm runoff volumes, peak flows, and flashiness; and (2) decreasing baseflow volumes and low flows. Although studies of urbanizing watersheds consistently show the increasing surface runoff and flashiness effect, the presumed complementary response of reduction in baseflow and low flows has not been clearly demonstrated. This paper describes streamflow changes in 46 small (< 250 sq km) urbanizing watersheds throughout the northeast U.S. megalopolis. A variety of measures of annual flow volume, flow duration, and flashiness are used to characterize streamflow regimes. Results are interpreted in terms of response patterns comprised of combinations of temporal trends in the annual flow measures. Trends are assessed using the nonparametric Mann-Kendall test. Although a range of response patterns are identified, the most common (14 out of the 46 streams) was that of increasing stormflow or flashiness index coupled with stable baseflow and 7-day low flows. Only four streams displayed the expected pattern of increasing stormflows and flashiness with declining baseflows and low flows. The trends in a single flow measure most frequently identified were increasing annual flashiness index (32 streams) and increasing annual stormflow volume (27 streams). Baseflow volume declined in five streams and increased in six, while 7-day low flows declined in 13 streams and increased in 11, indicating no consistent pattern in baseflow and low flow trends in these urbanizing watersheds.
H11E-0806
Intercomparsion of global hydrological models in terms of water storage simulations
Global hydrology modeling is an indispensable tool to study hydrological processes on continental scales. Furthermore, the output of global hydrological models provides an important input for studies on water availability or climate change. Until now, differences between global hydrological models are larger than predicted signals within many regions. This challenges the reliability of single model predictions. In order to understand reasons and sources of these differences, we compare the output of total water storage variations as well as groundwater, soil, snow and canopy storages simulated with three global hydrological models: the Global Land Data Assimilation System (GLDAS), the Land Dynamics model (LaD) and the WaterGAP Global Hydrology Model (WGHM). The main source of model inconsistency originates from the differences in global simulations of soil moisture. The differences between the models are mainly due to different model strategies (including the definition of storage compartments), different process formulations and errors in the input data. We suggest improving model simulations by an increased effort into research of process understandings on continental scales. Furthermore, a successful and world-wide integration of satellite observations of hydrological variables into these models is desirable to reduce uncertainties in global hydrological simulations. For instance, the GRACE (Gravity Recovery and Climate Experiment) mission depicts a useful measurement system to detect and assimilate total water storage changes on the continents.
H11E-0807
Initializing Weather Research and Forecasting (WRF) model with land surface conditions from the Terrestrial Observation and PredictionSystem (TOPS)
Weather forecasting models have been shown to exhibit a strong sensitivity to land surface conditions, particularly soil moisture. However, the lack of robust estimates of soil moisture at appropriate time and space scales has been a persistent problem. Terrestrial Observation and Prediction System (TOPS) integrates surface weather observations and satellite data with ecosystem simulation models to produce spatially and temporally consistent nowcasts and forecasts of land surface conditions such as soil moisture, evapotranspiration, vegetation stress and photosynthesis. To extend TOPS capabilities beyond estimating ecosystem rocesses, we integrated TOPS with Weather Research Forecasting (WRF) model to evaluate the utility of TOPS-derived surface conditions such as soil moisture in weather forecasting. TOPS land surface schemes are based on a well-calibrated ecosystem model, Biome-BGC, for simulating water and carbon budgets. One of the advantages of TOPS is its flexibility, which enables it to ingest data from a variety of sensors and surface networks, and thus we can provide the surface conditions to users from historical to near real-time, and for spatial scales ranging from 1km and up. We ran the TOPS-WRF system over California for several days during 2007. The results show TOPS-WRF simulations are consistently better than default WRF simulations, particularly over the dry season when spatial variability in soil moisture becomes a significant factor in influencing local energy balance.
H11E-0808 [WITHDRAWN]
Simulation of Radar Rainfall Fields: A Random Error Model
Precipitation is a major input in hydrological and meteorological models. It is believed that uncertainties due to input data will propagate in modeling hydrologic processes. Stochastically generated rainfall data are used as input to hydrological and meteorological models to assess model uncertainties and climate variability in water resources systems. The superposition of random errors of different sources is one of the main factors in uncertainty of radar estimates. One way to express these uncertainties is to stochastically generate random error fields to impose them on radar measurements in order to obtain an ensemble of radar rainfall estimates. In the method introduced here, the random error consists of two components: purely random error and dependent error on the indicator variable. Model parameters of the error model are estimated using a heteroscedastic maximum likelihood model in order to account for variance heterogeneity in radar rainfall error estimates. When reflectivity values are considered, the exponent and multiplicative factor of the Z-R relationship are estimated simultaneously with the model parameters. The presented model performs better compared to the previous approaches that generally result in unaccounted heteroscedasticity in error fields and thus radar ensemble.
H11E-0809
AMSR-E at the NSIDC DAAC: Updates to Products and Delivery Systems
The Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) is a mission instrument
launched aboard NASA's Aqua Satellite on 4 May 2002. It is a multichannel passive microwave radiometer
that is capable of measuring geophysical variables in the global water cycle, such as snow, sea ice, sea
surface temperature, precipitation and soil moisture, providing finer spatial resolution than previously
possible with spaceborne microwave radiometers. The National Snow and Ice Data Center (NSIDC)
Distributed Active Archive Center (DAAC) archives and distributes all AMSR-E standard products, including
Level 1A, 2, and 3 data.
Over the past 6 years, AMSR-E algorithm refinements by the Science Team and reprocessing campaigns
have led to improved and expanding research applications. Additionally, enhancements made to data
discovery and delivery by NSIDC have benefited existing users as well as reached new audiences. Many of
NSIDC's services target the increasing challenge of efficient data access and analysis
of an expanding satellite record. The recent changes to the AMSR-E products as well as the data services
offered by NSIDC will be highlighted.
http://nsidc.org/data/amsre/
H11E-0810
Multiple-Criteria Calibration of a Distributed Model Using Prior Information
The high dimensionality of parameter search space can be treated by utilizing a priori information about the parameters. A common trend that is adopted in the calibration of distributed hydrologic models is to adjust a priori parameter fields by a scalar multiplier. This approach, however, has many obvious limitations. For example the variance of the parameter distribution changes in proportion to the value of the constant multiplier, which is not always desirable. In addition, any parameter values lying close to the bounds (the range of physically permissible parameter values), posses a severe restriction on the calibration process - by restricting the range of values by which the multiplier can change. Instead of just adjusting the parameter field by a scalar multiplier, this research explores the advantages (or disadvantages) of using a combination of a scalar multiplier, an additive constant and a non linear transformation, on a priori parameter information, to calibrate a distributed hydrologic model by using a commonly available multiple- criteria optimization scheme. Specifically this study will strive to answer, following questions, (1) Is there any advantage of using the combination of three against the more parsimonious approach of calibrating only the multiplier or an additive constant? (2) Does the increase in the degrees of freedom impose parameter identifiability problem, if it does are there any methods (for example, use of regularization) to address this problem? (3) How can the restriction on the parameter bounds, which can be a bigger problem if the parameter fields are modified by the combination of three, be properly addressed? What is the impact of introducing a squashing function (function that restricts the parameters from going out of the bounds) to the calibration problem?
H11E-0811
Relating Hydrologic Homogeneity to Watershed Characteristics
To estimate the magnitude and frequency of flood flows at ungauged sites, space is traded for time using a regional frequency analysis. This requires the delineation of homogeneous regions in which the flood regime is sufficiently similar to allow the spatial transfer of information to ungauged sites. However, the ability to do so with adequate precision is hindered by our limited knowledge of the physical properties and mechanisms that produce flood flows. In order to improve our understanding of the underlying relationships among basin characteristics and flood quantiles, and thus improve the precision of flood quantile estimates at ungauged sites, this research (1) identifies association networks between basin characteristics and flood quantiles, as well as among the basin characteristics, (2) identifies the set of basin characteristics that best characterizes the regime of flood flows, and (3) quantifies the impact of the choice of similarity measures and classification technique on the delineation of homogeneous regions and flood risk estimates for ungauged sites. Using data for 162 sites in South Carolina, multivariate statistical methods (such as cluster analysis and principal component analysis) were employed to delineate regions based on their physiographic and climatic characteristics. The importance of each basin characteristic in the homogenization process is subsequently inferred. Also, the stability and robustness of the homogeneous groups with time and space is investigated.
H11E-0812
HIERARCHICAL BAYESIAN NETWORK BASED REGIONAL FREQUENCY ANALYSIS
We developed regional frequency analysis based on Hierarchical Bayesian Network (HBN) and scaling theory. Many recording rain gauges over South Korea were used for the analysis. First, a simple scaling approach combined with Gumbel distribution was employed to derive regional formula for frequency analysis. Second, HBN model was used to represent additional information about the regional structure of the scaling parameters, specifically the location parameter and shape parameter. The location and shape parameters of the Gumbel distribution were estimated by utilizing scaling properties in a regression framework, and the scaling parameters linking the parameters (location and shape) to various duration times were simultaneously estimated. Next, we consider that the regression coefficient associated with scaling properties for each station comes from a common distribution with a common mean and variance. A Markov Chain Monte Carlo (MCMC) procedure is used, and parameter and model uncertainty are both assessed as a byproduct of the estimation process. The proposed model revealed that the regional frequency analysis combined with HBN and scaling properties have good performances in terms of establishing regional IDF curves. Acknowledgements This study was supported by ¢®¡ÆResearches on national water security in preparation for climate change¢®¡¾ of MLTM¢®¡¾.
H11E-0813
Vortex Characteristic and Flow Discharge In Vortex Settling Chamber
In water treatment field, separation of sediment from raw water is one of the most important problems we must face today, especially separation of fine sediment particle from muddy water ¡V water with very high sediment concentration in natural resources such as river, reservoir, etc. There are so many different methods to solve this problem including tunnel type, vortex tubes, rectangular settling basins and the vortex type settling chamber. Among them the vortex settling chamber has recently studied so much because of its advantage. The vortex settling chamber is a device which is used to extract sediment from the diverted water by the vortex flow and centrifugal force in chamber. It can be said that vortex settling basin is an economical, efficient, and water-conserving choice compared with the other available devices especially for excluding fine suspended sediment particles. This research presents the new model of vortex settling chamber which will be focused on the separation of fine sediment from muddy water. This paper firstly presents the model in detail and some experimental cases which are carried out in this study. The relationship between flow discharge and water level will be considered and then some respective results will be presented and discussed. Finally, some conclusions are made about vortex characteristic in chamber as well as its effect on flow discharge.
H11E-0814
Comparison Study of Rainfall Data Using RDAPS Model and Raingauge Data
Recently, climate change has been observed in Korea as well as in the entire world. The rainstorm has been gradually increased and then the damage has been grown. It is getting important to predict short-term rainfall. The Korea Meteorological Administration(KMA) generates numerical model outputs which are computed by Global Data Assimilation and Prediction System(GDAPS) and Regional Data Assimilation and Prediction System(RDAPS). The KMA predicts rainfall using RDAPS results. RDAPS model generates 48 hours data which is organized 3 hours data accumulated at 00UTC and 12UTC. RDAPS results which are organized 3 hours time scale are converted into daily rainfall to compare observed daily rainfall. In this study, 9 cases are applied to convert RDAPS results to daily rainfall data. Finally, the best case which gives the close value to the observed rainfall data is obtained using the absolute relative error especially for the Keum River basin in Korea.
H11E-0815
Evapotranspiration in the Mackenzie River Basin Determined From GRACE and Auxiliary Hydrological Datasets
The Mackenzie River is the largest North American river supplying freshwater to the Arctic Ocean. Changes in this freshwater supply have the potential to significantly impact the global climate system through alterations in the salinity of the Arctic Ocean, which in turn drives the thermohaline circulation. This makes the hydrology of the Mackenzie River Basin (MRB) a critical region for studying the global climate system. In the present study, we investigate water storage variability within the MRB from 2003 to 2008 using the Gravity Recovery and Climate Experiment (GRACE) data. Recovery of water storage in the MRB is more complex than that of other basins due to glacial isostatic adjustment (GIA) from the Laurentide ice sheet. Contamination of the water storage signal by uplift due to GIA is removed using a signal estimated from the ICE-5G ice sheet/Earth model which yields predictions that are in agreement with the most recent gravimetric geoid model rates of the region. We then combine the corrected water storage time history with Climate Prediction Center Merged Analysis of Precipitation and Mackenzie River discharge measurements to estimate regional evapotranspiration. To determine the accuracy of the measured evapotranspiration it is compared with estimates from the GLDAS NOAH land surface model and other non-GRACE based studies. After accounting for GIA, we find that the water storage variability has no significant long term (5 year) trend. We also find good agreement between the GLDAS-estimated and measured periodic and constant components of the evapotranspiration. However GLDAS estimates an increasing linear trend in the evapotranspiration. The stability of the water storage variability is noteworthy as it implies that recent Arctic environmental changes have not severely affected water storage in the MRB region over the past five years. The finding of GLDAS overestimating the rate of change of the evapotranspiration rate could be significant to future updates of the model.
H11E-0816
WaterNet:The NASA Water Cycle Solutions Network
Water is essential to life and directly impacts and constrains society's welfare, progress, and sustainable
growth, and is continuously being transformed by climate change, erosion, pollution, and engineering.
Projections of the effects of such factors will remain speculative until more effective global prediction systems
and applications are implemented. NASA's unique role is to use its view from space to improve water and
energy cycle monitoring and prediction, and has taken steps to collaborate and improve interoperability with
existing networks and nodes of research organizations, operational agencies, science communities, and
private industry. WaterNet is a Solutions Network, devoted to the identification and recommendation of
candidate solutions that propose ways in which water-cycle related NASA research results can be skillfully
applied by partner agencies, international organizations, state, and local governments. It is designed to
improve and optimize the sustained ability of water cycle researchers, stakeholders, organizations and
networks to interact, identify, harness, and extend NASA research results to augment Decision Support Tools
that address national needs.
http://crew.iges.org/
H11E-0817
Patterns Of Moisture Storage During Canadian Prairie Drought
Comprehensive studies of soil moisture storage patterns during drought episodes and normal years on the Canadian Prairie are rare. These studies have become increasingly imperative and desirable for an understanding and quantification of the influences of the land surface moisture on atmospheric processes. These influences or "memory" of the soil moisture may play an important role under conditions of extreme climate such as drought and flood. The recollection of a wet or dry anomaly by the soil moisture memory is a fundamental component of any regional land-atmosphere interactions, which possess significant implications for seasonal forecasting. The 13,000km2 Upper Assiniboine River Basin in Central Saskatchewan with its outlet at Kamsack is the domain of this study; via deploying a land surface model variously known as the Variable Infiltration Capacity/Xinanjiang/ARNO model driven offline both in the water and energy balance modes, it was possible to capture the dynamics and seasonal response of the soil moisture storage up to a depth of about 1-metre. Meteorological inputs required to drive the model were retrieved respectively from Environment Canada and the North American Regional Reanalysis (NARR) dataset at daily and sub-daily time steps correspondingly. The North American Land Data Assimilation System (NLDAS) served as the repository from which the soil and vegetation parameters were obtained. The patterns in seasonal and inter-annual soil moisture storage as well as changes in the total water storage anomaly averaged over the entire basin were captured during a period of 11 years commencing 1994. The role of the observed patterns in the regional land-atmosphere interactions is being assessed to ascertain the relevance of the inherent memory in soil moisture as one of the slow drivers of the Canadian Prairie regional climate system with the key objective of attaining a better understanding of drought evolution, continuation and eventual cessation over this region.
H11E-0818
The Impact of Corps Flood Control Reservoirs in the June 2008 Upper Mississippi Flood
The US Army Corps of Engineers is responsible for a multitude of flood control project on the Mississippi River and its tributaries, including levees that protect land from flooding, and dams to help regulate river flows. The first six months of 2008 were the wettest on record in the upper Mississippi Basin. During the first 2 weeks of June, rainfall over the Midwest ranged from 6 to as much as 16 inches, overwhelming the flood protection system, causing massive flooding and damage. Most severely impacted were the States of Iowa, Illinois, Indiana, Missouri, and Wisconsin. In Iowa, flooding occurred on almost every river in the state. On the Iowa River, record flooding occurred from Marshalltown, Iowa, downstream to its confluence with the Mississippi River. At several locations, flooding exceeded the 500-year event. The flooding affected agriculture, transportation, and infrastructure, including homes, businesses, levees, and other water-control structures. It has been estimated that there was at least 7 billion dollars in damages. While the flooding in Iowa was extraordinary, Corps of Engineers flood control reservoirs helped limit damage and prevent loss of life, even though some reservoirs were filled beyond their design capacity. Coralville Reservoir on the Iowa River, for example, filled to 135% of its design flood storage capacity, with stage a record five feet over the crest of the spillway. In spite of this, the maximum reservoir release was limited to 39,500 cfs, while a peak inflow of 57,000 cfs was observed. CWMS, the Corps Water Management System, is used to help regulate Corps reservoirs, as well as track and evaluate flooding and flooding potential. CWMS is a comprehensive data acquisition and hydrologic modeling system for short-term decision support of water control operations in real time. It encompasses data collection, validation and transformation, data storage, visualization, real time model simulation for decision-making support, and data dissemination. The system uses precipitation and flow data, collected in real-time, along with forecasted flow from the National Weather Service to model and optimize reservoir operations and forecast downstream flows and stages, providing communities accurate and timely information to aid their flood-fighting. This involves integrating several simulation modeling programs, including HEC-HMS to forecast flows, HEC-ResSim to model reservoir operations and HEC-RAS to compute forecasted stage hydrographs. An inundation boundary and depth map of water in the flood plain can be calculated from the HEC-RAS results using ArcInfo. By varying future precipitation and releases, engineers can evaluate different "What if?" scenarios. The effectiveness of this tool and Corps reservoirs are examined.
H11E-0819
Automated Upscaling of River Networks for Macroscale Hydrological Modeling
Regional upscaling of river networks and flow directions to coarse spatial scales commensurate with global climate models (GCMs) is necessary for representing the lateral movement of water, sediment and nutrients in macroscale hydrological modeling studies. Most upscaling methods involve time-intensive and subjective manual corrections of disconnected river segments and flow paths defined at relatively coarse spatial scales. We developed a new approach for automated extraction and spatial upscaling of river networks and flow directions from relatively fine scale DEM information. Model outputs include flow accumulation, flow direction and river network structure. The algorithm determines downstream hierarchical flow paths for each grid cell while preserving predominant flow paths defined from the baseline, fine scale DEM. Downstream flow paths and directions are prioritized according to upstream contributing drainage areas. Additional constraints are defined to minimize the occurrence of broken or false river segments. The algorithm prioritizes river channels by length and selects the longest effective stem river segment for each grid cell to collect water from upstream areas. The algorithm also maintains consistency in basin area calculations by minimizing the growth of bigger basins and boundary areas at coarser spatial scales. We applied the algorithm to produce a series of global river datasets at variable spatial resolutions including 1/16, 1/8, 1/4, 1/2, 1, and 2 degrees. The model results indicate several advantages over other commonly used approaches, including: (1) accurate, automated extraction of river network and flow paths at any spatial scale without the need for intensive manual correction; (2) consistency of flow path shape, flow path density, drainage area (basin area), and (3) flow distance between the upscaled river networks and baseline fine scale river network/flow direction information.
H11E-0820
Research Priorities for Operational Hydrologic Forecasting: NWS Strategic Plan and Recent Accomplishments
This paper presents the main research priorities for hydrologic research within the National Weather Service. The research directions are framed by the Strategic Science Plan, adopted in early 2008, which introduced long-term research goals on: watershed modeling, forcings, anthropogenic and natural perturbations of the hydrologic cycle, ensemble forecasting, data assimilation, verification, and social science research. Topics to be covered in this presentation include plans, current work and recent accomplishments on those topics, including: increased use of satellite-based observations, improvements to radar precipitation observations, development of physically based hydrologic modeling, coupled groundwater and surface water hydrologic modeling. The main objective of this presentation is to elicit a healthy discussion among the scientific community on these research priorities, and to encourage extramural research in those topics.
H11E-0821
Estimating Runoff From Roadcuts With a Distributed Hydrologic Model
Roads can have a substantial effect on hydrologic patterns of forested watersheds; the most noteworthy being the resurfacing of shallow groundwater at roadcuts. The influence of roads on hydrology has compelled hydrologists to include water routing and storage routines in rainfall-runoff models, such as those in the Distributed Hydrologic Soil Vegetation Model (DHSVM). We tested the ability of DHSVM to match observed runoff in roadcuts of a watershed in the Coast Range of Oregon. Eight roadcuts were instrumented using large tipping bucket gauges designed to capture only the water entering the roadside ditch from an 80-m long roadcut. The roadcuts were categorized by the topography of the upstream hillside as either swale, planar, or ridge. The simulation was run from December 2002 to December 2003 at a relatively fine spatial resolution (10-m). Average observed soil depths are 1.8-m across the watershed, below which there lies deep and highly weathered sandstone. DHSVM was designed for relatively impermeable bedrock and shallow soils; therefore it does not provide a mechanism for deep groundwater movement and storage. In the geologic setting of the study basin, however, water is routed through the sandstone allowing water to pass under roads through the parent material. For this reason a uniformly deep soil of 6.5-m with a decreased decay in conductivity with depth was used in the model to allow water to be routed beneath roadcuts that are up to 5.5-m in height. Up to three, typically shallow, soil layers can be modeled in DHSVM. We used the lowest of the three soil layers to mimic the hydraulically-well-connected sandstone exposed at deeper roadcuts. The model was calibrated against observed discharge at the outlet of the watershed. While model results closely matched the observed hydrograph at the watershed outlet, simulated runoff at an upstream gauge and the roadside ditches were varied and often higher than those observed in the field. The timing of the field observed events, although infrequent compared to simulated events, did match simulated event timing when they occurred. Our results agree with earlier findings that highlight the challenge of validating distributed hydrologic models at multiple points.
H11E-0822
Estimating Maximum Possible Point Rainfall and Flooding in Western Texas
Comparison of magnitude of record floods in small to medium-sized (<1- 100 km2) rural drainage basins in western Texas suggests that record flooding on most watersheds resulted from 150 to 300 mm of rainfall in 12-24 hours. Rainfall intensity and duration and area of watershed are the most important variables in magnitude of flooding on small watersheds. The probable maximum precipitation for this time interval, however, is most likely in the range of 300 to 600 mm. This estimate is based on point rainfall records in southwestern Texas, central Oklahoma and eastern Colorado. Recently documented point precipitation records suggest that the probable maximum precipitation is much greater than has been recorded at most weather stations during the 100 plus years of weather records in this part of Texas. The greatest calendar day rainfall at Del Rio, Texas, for example, changed in 1998 from 223 mm (recorded in 1935) to 432 mm on August 23, 1998—an increase of more than 93%. Even this new rainfall record is probably significantly below the maximum probable precipitation. Probable maximum precipitation rates are probably determined by physical and meteorological limits, however, regional escarpments, and canyons cut into those escarpments, play a role in localizing and maintaining optimum conditions for precipitation and runoff. Assuming a probable maximum 1-Day precipitation of 300 to 600 mm, the probable peak discharge resulting from such an event would be 4 to 6 times the calculated 100 year flood and 2 to 3 times the calculated 500 year flood on most watersheds.
H11E-0823
Use of the Continuous Slope-Area Method to Estimate Runoff Through Ephemeral Stream Channels in SE Arizona
Quantifying discharge and associated ground-water recharge from ephemeral flow events in the desert southwest USA is of increasing importance because of mandates to achieve sustainability of water resources; however, low-cost techniques for accurate and continuous monitoring of ephemeral flows are not established. The continuous-slope area (CSA) method extends the well-known slope area method (used to develop peak-flow hydrographs) to permit complete-event discharge hydrographs to be developed. The method was tested by installing 11 CSA gaging sites within three sand-bedded ephemeral tributaries to the San Pedro River near Sierra Vista and Fort Huachuca, Arizona. CSA gages were located in reaches with 1) slowly varying flow paths, 2) total channel length at least nine times the channel width, 3) nearly constant cross-widths along the reach, and, 4) accessibility. A single CSA gage required three pressure transducers to be installed along the selected reach, separated by flow-path lengths about five times the channel width. Perforated pipes were driven 1 to 1.5 meters into bed sediments at a downstream angle of 45 degrees. Transducers were set in pipes with sensors located five to 10 centimeters below the channel bed. Channel cross-sections, cutting through each transducer location, were surveyed after installation and after significant flow events. For an independent check of stage/discharge, one gage was installed upstream of a broad-crested weir; this gage was fitted with a staff-plate to allow confirmatory observations. The USGS slope-area-computation program was modified to compute continuous discharge hydrographs, using survey data, stage time series, and estimates of channel roughness. The highest stage measured was 1.3 meters above the bed with an associated peak discharge of 34 cubic meters per second, and with a sustained flow of 28 cubic meters per second for 10 minutes. Runoff and ground-water recharge from flow events will be estimated using transmission and infiltration losses either measured directly or by rainfall/runoff modeling, with the overall aim of informing efforts to attain sustainable ground-water use.
H11E-0824
Distributed Hydrology Soil Vegetation Model (DHSVM) and Sediment Discharge in a Small, Timber Production Watershed, Humboldt County, California
Sediment impacts to streams and rivers, either as suspended sediment concentration (SSC), or as aggradation, are well documented in the Pacific Northwest. Fishery stocks, estuarine, infrastructural and wildland resources can be negatively impacted. The causes and reasons for sedimentation of river resources are varied and diverse: tectonic setting - the relative rapid uplift of the study region produces a dominant erosional process of landsliding and mass wasting; regolithic setting - the relatively recent uplift of marine sediments has produced local formations of poorly and moderately consolidated soils, and lithic melanges that are naturally susceptible to erosion; climatic/geographic setting - coastal locations are subject to seasonal delivery of a relatively high average annual precipitation serving to transport available sediment; and finally, management setting - the activities that serve to make sediment available for transport to the river channel, forest road building and harvesting activities associated with timber production, agriculture, gravel mining, and fire management. The reduction of sediment loading can be accomplished through restoration activities like forest road decommissioning or riparian area revegetation. The need to prioritize restoration efforts is confounded by a lack of hydrographic and sediment discharge data, the complex terrain, and the inability to predict the effects of these activities on a dynamic scale. The Distributed Hydrology Soil Vegetation Model (DHSVM) has been developed to model watersheds using spatially explicit geographical data coupled with physically based hydrologic equations. DHSVM simulates watershed processes across a grid on a cell-by-cell manner. The most recent development within the DHSVM includes a mass wasting / sediment production and channel routing module which allows prediction of total sediment loading in a forest basin. We are applying DHSVM to the McReady sub-basin of Freshwater Creek, Humboldt County, California, utilizing site specific precipitation, hydrographic, and sediment data. Hydrographic and sediment discharge data from 2002 to present are used to train and validate the model. A detailed sediment source inventory from both the road and stream courses further informs the model process and parameterization of sediment production and mobilization within the watershed. The availability of continuous discharge and sediment loading via turbidity threshold stations (TTS) allows validation of the model's performance on multiple levels: average annual, monthly, or weekly sediment loading, and on an event by event basis. Effective validation permits the use of the model to understand the effects of future management strategies, i.e. timber harvest, road construction or decommissioning on a site-specific basis, and to model landscape effects of wildfire and climate change scenarios on watershed functions.
H11E-0825
Managing River Resources: A Case Study Of The Damodar River, India
The Damodar River, a subsystem of the Ganga has always been a flood-prone river. Recorded flood history
of the endemic flood prone river can be traced from 1730 onwards. People as well as governments through
out the centuries have dealt with the caprices of this vital water resource using different strategies. At one
level, the river has been controlled using structures such as embankments, weir, dams and barrage. In the
post-independent period, a high powered organization known as the Damodar Valley Corporation (DVC),
modeled on the Tennessee Valley Authority (TVA) came into existence on 7th July 1948. Since the
completion of the reservoirs the Lower Damodar has become a 'reservoir channel' and is now identified by
control structures or cultural features or man made indicators. Man-induced hydrographs below control
points during post-dam period (1959-2007) show decreased monsoon discharge, and reduced peak
discharge. In pre-dam period (1933-1956) return period of floods of bankfull stage of 7080 m3/s had a
recurrence interval of 2 years. In post-dam period the return period for the bankfull stage has been
increased to 14 years. The Damodar River peak discharge during pre-dam period for various return periods
are much greater than the post-dam flows for the same return periods. Despite flood moderation by the DVC
dams, floods visited the river demonstrating that the lower valley is still vulnerable to sudden floods.
Contemporary riverbed consists of series of alluvial bars or islands, locally known as mana or char lands
which are used as a resource base mostly by Bengali refugees. At another level, people have shown great
resourcefulness in living with and adjusting to the floods and dams while living on the alluvial bars. People
previously used river resources in the form of silt only but now the semi-fluid or flexible resource has been
exploited into a permanent resource in the form of productive sandbars.
Valuable long-term data from multiple sources has been used in this study to track flow regime and
sedimentation characteristics. Data from topographical maps, cadastral or mouza maps, and satellite images
has been consolidated. Significant stress has been given on extensive and intensive field survey in order to
assess human perception, adaptability and resource management in the sandbars or char lands. The
Damodar River is located in West Bengal, India but the findings on the controlled Lower Damodar are not
exclusive to this river. These findings may help in managing water resources in other regulated rivers in India
or outside India. The primary objectives of this paper have been to trace the impact of control measures on
discharge, sedimentation characteristics and consequent changes in the perception and adjustment of the
riverbed occupiers to life with floods and dams. In this age of heightened environmental awareness, we all
know that the survival of our civilization depends on rational and constructive maintenance and use of our
river resources. The major challenge in the coming decade is to develop a holistic and sustainable river
management system that will be environmentally accountable, socially acceptable and economically feasible.
The primary issue to be addressed, therefore, is not whether dams are needed but how a river system is
cared for in the presence of floods, dams and islanders. River resources should be treated as economic
assets since ongoing economic development depends on a riverine regime that is ecologically sound. These
worthwhile goals, however, will remain out of reach unless we have effective government policy and the legal
structure to support it.
http://www.agu.org.ManagingRiverResources
H11E-0826
Retardance coefficient of vegetated channels estimated by the Froude number
Manning Equation is widely adopted to estimate open channel flows, and selecting retardance coefficient is always one of the most difficult task for estimating discharge. In cases of estimating accurate retardance coefficient values of vegetated channels, countless trial and error are to be made before reaching conclusive results due to conditions created by various aquatic plants. The majority of past studies on this subject, however, are established based on terrestrial plants and plastic moulds as laboratorial factors, and only few are done with natural aquatic vegetations. Hence, in this study, two different types of natural aquatic plants are applied to estimate retardance coefficients; and the result indicates that each type of plant affects differently in terms of flow resistance. In addition, analyses of hydraulic parameters show that there are significant correlations between retardance coefficient and velocity, plant lodging height, and the Froude number. Thus the Froude number can be used to accurately estimate the retardance coefficient of vegetated channels.
H11E-0827
Decadal variations of hydrological processes under the impact of urbanization
A simulated urbanized area with 15x15 km2, representing ChaiYi City, has proved to produce up to 3 times more sensible heat flux around noon time than that of a non-urbanized area in the central Taiwan. This effect, therefore, can have significant impact on locations of local summer thunderstorms and precipitation over sensitivity tests. However, the precipitation system move upward and northward along the mountain range to the east of the study area instead of the downwind direction,. Both decadal monthly mean precipitation and precipitation days, therefore, have been found increased up to 11% in the east and northeast of the Chiayi area than the west during the summer periods since 1960s. In addition, we also found that the decadal mean precipitation has been decreasing to 9% in the further east toward the mountain rage since 1960s. This uneven spatial distribution indicates that more summer thunderstorms would have happened before they reached the mountain range by the effect of heat island. This spatially and temporally variation of hydrological processes in the study area has posted a new challenge on the estimation of erosion rate based on suspended sediment transport.