Development of a large-sample watershed-scale hydrometeorological data set for the contiguous USA: data set characteristics and assessment of regional variability in hydrologic model performance Hydrology and Earth System Sciences DOI 10.5194/hess-19-209-2015 14 January 2015 The focus of this paper is to (1) present a community dataset of daily forcing and hydrologic response data for 671 unimpaired basins across the contiguous United States that spans a very wide range of hydroclimatic conditions; and (2) provide a calibrated model performance benchmark using a common conceptual snow and hydrologic modeling system. This benchmark provides a reference level of model performance across a very large basin sample and highlights regional variations in performance. Read more
What causes cooling water temperature gradients in a forested stream reach? Hydrology and Earth System Sciences DOI 10.5194/hess-18-5361-2014 20 December 2014 This study demonstrates the processes by which instantaneous longitudinal water temperature gradients may be generated in a stream reach that transitions from moorland to semi-natural forest in the absence of substantial groundwater inflows. Water did not cool as it flowed downstream. Instead, temperature gradients were generated by a combination of reduced rates of heating in the forested reach and advection of cooler (overnight and early morning) water from the upstream moorland catchment. Read more
Dams on Mekong tributaries as significant contributors of hydrological alterations to the Tonle Sap Floodplain in Cambodia Hydrology and Earth System Sciences DOI 10.5194/hess-18-5303-2014 18 December 2014 Hydrological modeling and assessment tools were used to provide evidence of the expected hydrological alterations that hydropower development in the lower Mekong tributaries could bring to the Tonle Sap. The most significant alterations are in terms of water levels during the dry season and rates of water level rise/drop which are crucial for tree seed germination and fish migrations, and therefore major ecological disruptions are likely to follow. Read more
A virtual water network of the Roman world Hydrology and Earth System Sciences DOI 10.5194/hess-18-5025-2014 11 December 2014 Our virtual water network of the Roman World shows that virtual water trade and irrigation provided the Romans with resilience to interannual climate variability. Virtual water trade enabled the Romans to meet food demands from regions with a surplus. Irrigation provided stable water supplies for agriculture, particularly in large river catchments. However, virtual water trade also stimulated urbanization and population growth, which eroded Roman resilience to climate variability over time. Read more
Estimating degree-day factors from MODIS for snowmelt runoff modeling Hydrology and Earth System Sciences DOI 10.5194/hess-18-4773-2014 3 December 2014 In this paper, we propose a new method for estimating the snowmelt degree-day factor (DDFS) directly from MODIS snow covered area and ground-based snow depth data without calibration. Snow density is estimated as the ratio between observed precipitation and changes in the snow volume for days with snow accumulation. DDFS values are estimated as the ratio between changes in the snow water equivalent and difference between the daily temperature and a threshold value for days with snowmelt. Read more
Complex networks for streamflow dynamics Hydrology and Earth System Sciences DOI 10.5194/hess-18-4565-2014 20 November 2014 This study introduces the theory of networks, and in particular complex networks, to examine connections in streamflow dynamics. Monthly streamflow data from a network of 639 stations in the United States are studied. The connections are examined primarily using the concept of clustering coefficient, which quantifies the network’s tendency to cluster. The clustering coefficient analysis is performed with several different threshold levels based on correlations in streamflow between the stations. Read more
Historical impact of water infrastructure on water levels of the Mekong River and the Tonle Sap system Hydrology and Earth System Sciences DOI 10.5194/hess-18-4529-2014 17 November 2014 This paper analyses the historical water levels of the Mekong River and Tonle Sap system by comparing pre- and post-1991 daily observations from six stations along the Mekong mainstream from Chiang Saen (northern Thailand), to Stung Treng (Cambodia), and the Prek Kdam station on the Tonle Sap River. Read more
Analytical approach for predicting fresh water discharge in an estuary based on tidal water level observations Hydrology and Earth System Sciences DOI 10.5194/hess-18-4153-2014 17 October 2014 In this study, the authors investigate the influence of river discharge on tidal wave propagation in the Yangtze estuary with specific attention to residual water level slope. Read more
Integrated assessment of global water scarcity over the 21st century under multiple climate change mitigation policies Hydrology and Earth System Sciences DOI 10.5194/hess-18-2859-2014 6 August 2014 Water scarcity conditions over the 21st century both globally and regionally are assessed in the context of climate change and climate mitigation policies, by estimating both water availability and water demand within the Global Change Assessment Model, a leading community-integrated assessment model of energy, agriculture, climate, and water. Read more
On the future of journal publications in hydrology Hydrology and Earth System Sciences DOI 10.5194/hess-18-2433-2014 27 June 2014 A group of editors from hydrology journals discusses a number of actions to help strengthen publications and research in hydrology as a whole. Read more
