As a typical inland river basin in arid Northwest China, having distinct hydrological characteristics and severe and representative water problems, the Heihe River Basin (HRB) has attracted considerable research interest worldwide and in 2007 became a pilot basin of the G-WADI network of UNESCO/IHP. Many research programs have been conducted in the HRB since the 1980s, producing rich knowledge and data about the basin, which will be very helpful to further studies. This paper reviews research efforts related to hydrologic modeling and ongoing model integration studies performed in the HRB in recent years. Recently, an observation network covering the whole area and a Web-based data-sharing system have been established which can greatly improve data acquisition. This paper tabulates modeling activities in past years, including model ap- plications, model modifications and enhancements, and model coupling efforts. Also described is a preliminary modeling integration tool designed to quickly build new models, which has been developed for hydrologic modeling purposes. Challeng- es and issues confronted in current studies are discussed, pointing toward key research directions in the future.
There are only limited surface water resources available in the Heihe River Basin(HRB), a typical inland river basin in the arid region of northwestern China, where groundwater overexploitation is a serious problem. Groundwater has become one of main resources of fresh water in the HRB. In this paper, temporal and spatial variations of groundwater in the HRB are estimated by the Gravity Recovery and Climate Experiment(GRACE) satellites. Our analysis shows that groundwater storage in the HRB reaches its highest in the summer of 2005, and then begins to decline in the following years and reaches steady status in 2008. Spatially, groundwater shows a decline in the upper HRB in the first two years and a slight increase in the following years, while this phenomenon is reversed in the middle HRB where groundwater slightly increases in 2005 and then declines in the following three years. In the lower HRB, GRACE detects a continual increase in the full six-year period. This approach is proven successful when employed in the HRB and thus offers a new insight into monitoring groundwater variations in a river basin with limited or even without any observed data.
As an important forcing data for hydrologic models, precipitation has significant effects on model simulation. The China Meteorological Forcing Dataset(ITP) and Global Land Data Assimilation System(GLDAS) precipitation data are the two commonly used data sources in the Heihe River Basin(HRB). This paper focused on evaluating the accuracy of these two precipitation datasets. A set of metrics were developed to characterize the trend, magnitude, annual allocation, event matching, frequency, and spatial distribution of the two datasets. Meanwhile, such accuracy evaluation was performed at various scales, i.e., daily, monthly, and yearly. By comparing with observations, this study concluded that: first, both ITP and GLDAS precipitation data well represented the trends at corresponding sites, and GLDAS underestimated precipitation in most regions except the east tributary headwater region; second, unusual annual precipitation distribution was observed in both datasets with overestimation of precipitation in May through September and GLDAS appeared to be much severe; third, the ITP data seriously over-predicted the precipitation events; fourth, the ITP data have better spatial distribution than GLDAS in the upper reach area of HRB. Overall, we recommended ITP precipitation data for the land surface study in the upper reach of HRB.
