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26Abstract 27 During the past several decades, numerous reservoirs have been built across the world for a 28 variety of purposes such as flood control, irrigation, municipal/industrial water supplies, and 29 hydropower generation. Consequently, the timing and magnitude of natural streamflow have been 30 altered significantly by reservoir operations. In addition, the hydrological cycle is also modified 31 by land-use/land-cover change and by climate change. To understand the fine-scale feedback 32 between hydrological processes and water management decisions, a distributed hydrological 33 model embedded with a reservoir component is desired. In this study, a multi-purpose reservoir 34 module with predefined complex operational rules was integrated into the Distributed Hydrology 35Soil Vegetation Model (DHSVM). Conditional operating rules, which are designed to reduce 36 flood risk and enhance water supply reliability, were adopted in this module. The performance of 37 the integrated model was tested over the upper Brazos River Basin in Texas, where two U.S. 38Army Corps of Engineers reservoirs, Lake Whitney and Aquilla Lake, are located. The integrated 39 DHSVM was calibrated and validated using observed reservoir inflow, outflow, and storage data. 40The error statistics were summarized for both reservoirs on a daily, weekly, and monthly basis. 41Using the weekly reservoir storage for Lake Whitney as an example, the coefficient of 42 determination (R 2 ) was 0.85 and the Nash-Sutcliff Efficiency (NSE) was 0.75. These results 43 suggest that this reservoir module holds promise for use in sub-monthly hydrological simulations. 44 With the new reservoir component, the DHSVM provides a platform to support adaptive water 45 resources management under the impacts of evolving anthropogenic activities and substantial 46 environmental changes. 47 Keywords 48 Reservoir; DHSVM; Water resources; Operation rules 49 reservoirs (statistics based on Lehner et al. [29]). Compared with extracting water directly from 74 streams, a reservoir based water-supply system increases the supply reliability in most regions 75 [37]. However, global environmental/anthropogenic changes-such as climate change, land-76 cover/land-use change (LCLUC), and population growth-pose great challenges to the reservoir 77 systems [56]. More variable precipitation, constantly increasing temperatures, and more frequent 78 floods and droughts are all threatening the sustainability of water resource management [9] [64]. 79Meanwhile, water demands are increasing drastically driven by a fast-growing population [40]. 80To improve the adaptiv...
