3310 El Camino Ave.

Sacramento, CA, United States

3310 El Camino Ave.

Sacramento, CA, United States
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Kavvas M.L.,University of California at Davis | Ohara N.,University of California at Davis | Anderson M.L.,3310 El Camino Ave. | Yoon J.,Korea University
Journal of Hydrologic Engineering | Year: 2012

To establish a basinwide water management plan for the Tigris-Euphrates (TE) watershed, it is necessary to perform rigorous water balance studies of the whole watershed-at least for critical historical drought and flood conditions and under various water resources development scenarios. Water-balance studies over the watershed require climatic and hydrologic data sets, corresponding to historical critical flood and drought periods, at fine time and spatial grid resolutions provide the necessary hydroclimatic information. The Regional Hydroclimate Model of the Tigris-Euphrates (RegHCM-TE) and the associated geographic information system (GIS) were developed to downscale large-scale atmospheric data sets over the TE watershed and to reconstruct the aforementioned climatic and land hydrologic data sets at fine spatial and time increments. In RegHCM-TE, the earth system over the TE watershed is modeled as a fully coupled system of atmospheric processes aloft coupled with the atmospheric boundary layer, land-surface processes, surface and subsurface hydrologic processes, and the interactions among the various hydrologic and atmospheric processes. The parameters of the model are estimated by using existing global and local GIS data. By using the large-scale global historical atmospheric databases as its initial and boundary conditions, RegHCM-TE has been used to reconstruct historical hydroclimate data at a grid size of 15 km over the TE watershed, for which only very sparse hydrologic observations were available. RegHCM-TE and its model validation are described in this paper. © 2011 American Society of Civil Engineers.


Ohara N.,University of Wyoming | Jang S.H.,University of California at Davis | Kure S.,Tohoku University | Richard Chen Z.Q.,3310 El Camino Ave. | Kavvas M.L.,University of California at Davis
Journal of Hydrologic Engineering | Year: 2014

The energy and mass balance model for terrestrial ice and snow is an essential tool for the future projection of interannual snow and ice storage including glaciers. However, the snow models in the hydrologic engineering field have barely considered the long-term behavior of the snow and ice storage because the time scale of glacier dynamics is much longer than those of river flow and seasonal snowmelt. This paper proposes an appropriate treatment for inland glaciers as systems in dynamic equilibrium that stay constant under a static climate condition. It is conjectured that the snow and ice vertical movement from high-elevation areas to valleys (lower elevation areas) by means of wind redistribution, avalanches, and glacial motion may be considered as an equilibrator of the snow and ice storage system because it stimulates snow and ice ablation. In order to demonstrate this concept, a simple dynamic equilibrium model for regional to global scales is proposed and applied to the Pamirs. The interannual snow and ice storage in the Pamir Mountains may lose about half of their volume by the end of 21st century by the anticipated global warming based on nine selected general circulation model (GCM) projections. © 2014 American Society of Civil Engineers.


Ohara N.,University of California at Davis | Kavvas M.L.,University of California at Davis | Anderson M.L.,3310 El Camino Ave. | Yoon J.,Korea University
Journal of Hydrologic Engineering | Year: 2012

Several case studies of the Tigris-Euphrates (TE) river basin were performed to investigate the effects of various water resource utilizations on dynamic water balances of the watershed. A daily dynamic water balance model was developed to simulate water resource conditions corresponding to four utilization scenarios in the TE watershed: (1) pre-1970 natural conditions; (2) current levels of water resource development/utilization in Syria and Iraq while maintaining pre-1970 conditions in Turkey (i.e., natural, unobstructed flows from Turkey); (3) scenarios involving constant-discharge water release from the Turkish sector downstream on the basis of estimations of future water utilization in the Turkish sector of the TE watershed; and (4) minimum time-varying water releases from Turkey to meet current irrigation water demands in the downstream region. All water balance simulations reconstructed atmospheric and hydrologic conditions during historical critical drought and flood periods. Irrigation demands were estimated by using the Food and Agricultural Organization of the United Nations (FAO) method, with reconstructed atmospheric and crop distribution data derived from satellite observations. Operations of 15 major dams in the Syrian and Iraqi sectors of the TE watershed were dynamically simulated under several different flow regimes regulated and unregulated by the upstream country, Turkey. This study illustrates that irrigation water demands in Iraq and Syria can be effectively met by various constant-discharge water releases from the Turkish sector. Also, if the seasonality of irrigation water demands in the lower TE region is considered when scheduling water releases from Turkey, these releases can be decreased while still meeting the current irrigation water demands of downstream countries. Water diversion from the Tigris to the Euphrates through the Samarra-Thartar complex may provide significant freedom to optimize water allocation in this region. Additionally, because of the arid climate in the lower TE river basin, a considerable amount of water evaporates from the reservoirs. The analyses indicate that storing water in the upstream region seems to be more effective in reducing reservoir water evaporation compared to storing water in the downstream region because the small surface area-to-storage volume of the upstream TE reservoirs and the cooler climate in the upstream sector of the watershed. © 2011 American Society of Civil Engineers.


Kavvas M.L.,University of California at Davis | Ohara N.,University of California at Davis | Anderson M.L.,3310 El Camino Ave. | Yoon J.,Korea University
Journal of Hydrologic Engineering | Year: 2012

The Mesopotamian Marshlands used to be the largest wetland ecosystem in the Middle East and western Eurasia. These marshlands once covered more than 15,000-20,000 sq km with permanent lakes and marshes, seasonal marshes temporary marshes. Although the recent restoration efforts returned the marshes back to approximately 39% of their original spatial extent, the artificial drainage works have significantly reduced the marshes during the late 1980s and 1990s. The water resources development/utilization in the upstream regions of the Tigris-Euphrates (TE) River Basin has been considered as one of the causes for the damage of the marshland ecosystem. To assess the hydrologic conditions in the Mesopotamian Marshes under various water utilization scenarios, a marshland hydrologic model for the Hawr Al Hammar Marshes near the downstream end of the TE River Network has been developed in conjunction with the regional hydro-climate model of Tigris-Euphrates (RegHCMTE) Watershed and the water resources system model of the Euphrates-Tigris River Basin. This marshland hydrologic model accounts for rainfall, evapotranspiration, surface water inflows and outflows soil water inflows and outflows. In this paper, the marshland hydrologic model for the Hawr Al Hammar Marshes is described the reconstruction of historical marshland hydrologic data over Hawr Al Hammar Marshes by using the coupled TE modeling system is presented. By using the developed Mesopotamia Marsh model, the impact of various water resources utilization alternatives in the TE Basin on the hydrology of the Hawr Al Hammar marshes is quantified. The simulation results reveal that by treating the TE Basin as one hydrologic unit, where water is transferred from the Tigris to the Euphrates River to meet the irrigation water demands in the basin for various release scenarios from the Turkish sector, it is possible to sustain the Al Hammar Marshes at their pre-dam-construction (pre-1970) conditions in the TE Basin under severe hydro-climate conditions of the historical critical dry period. © 2011 American Society of Civil Engineers.

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