Assessing economic impacts of China’s water pollution mitigation measures through a dynamic computable general equilibrium analysis.

In this letter, we apply an extended environmental dynamic computable general equilibrium model to assess the economic consequences of implementing a total emission control policy. On the basis of emission levels in 2007, we simulate different emission reduction scenarios, ranging from 20 to 50% emission reduction, up to the year 2020. The results indicate that a modest total emission reduction target in 2020 can be achieved at low macroeconomic cost. As the stringency of policy targets increases, the macroeconomic cost will increase at a rate faster than linear. Implementation of a tradable emission permit system can counterbalance the economic costs affecting the gross domestic product and welfare. We also find that a stringent environmental policy can lead to an important shift in production, consumption and trade patterns from dirty sectors to relatively clean sector

Detection and attribution of hydrological changes in different climatic and geomorphic regions of China

Through large-scale hydrological simulation, understanding the impact of different climatic and geomorphic conditions on hydrological variables is valuable for water and land management. However, the related study is still a challenge due to strong environmental diversity in large scale region. The physically-based, national-scale hydrological model in China was developed and validated, which considered the spatial heterogeneity of climatic and geomorphic conditions. Using the model, hydrological differences during the period 1956–2020 in 21 representative basins located in nine climatic zones and four geomorphic regions were quantified. Results showed that: 1) mean annual precipitation was strongly positively correlated with mean actual evapotranspiration, and both increased gradually from north to south. Interestingly, as annual precipitation increases, precipitation tended to be more evenly distributed. In recent decades, the northern river basins have been warming and drying, while the Heihe River basin and the cold northeast regions were under climatic warming and wetting; 2) the spatial distribution of streamflow was consistent with precipitation, but their trends were different. In cold regions affected by frozen soil, the streamflow tended to increase. On the contrary, the basins located in the Warm Temperate Zone with intense human activities and fragile ecosystem had a significant decrease in natural streamflow. As for the streamflow components, the frozen soil and karst structures contributed to the increase of the baseflow index (BFI); 3) The streamflow increase or reduction in 86% of the basins was dominated by climate change, as the contribution rate varied from 51.4% to 95.7%. Affected by the Grain to Green Programme, the streamflow of the Weihe River basin reduced significantly while the BFI increased. However, the reduction of forest, grassland and wetland areas dominated streamflow increase in the Huaihe, and Hulan River basins, and the rates were 65.3% and 66.1%, respectively

An Eco-Hydrological Model-Based Assessment of the Impacts of Soil and Water Conservation Management in the Jinghe River Basin, China

Many soil and water conservation (SWC) measures have been applied in the Jinghe River Basin to decrease soil erosion and restore degraded vegetation cover. Analysis of historical streamflow records suggests that SWC measures may have led to declines in streamflow, although climate and human water use may have contributed to observed changes. This paper presents an application of a watershed-scale, physically-based eco-hydrological model—the Regional Hydro-Ecological Simulation System (RHESSys)—in the Jinghe River Basin to study the impacts of SWC measures on streamflow. Several extensions to the watershed-scale RHESSys model were made in this paper to support the model application at larger scales (>10,000 km2) of the Loess Plateau. The extensions include the implementation of in-stream routing, reservoir sub-models and representation of soil and water construction engineering (SWCE). Field observation data, literature values and remote sensing data were used to calibrate and verify the model parameters. Three scenarios were simulated and the results were compared to quantify both vegetation recovery and SWCE impacts on streamflow. Three scenarios respectively represent no SWC, vegetation recovery only and both vegetation recovery and SWCE. The model results demonstrate that the SWC decreased annual streamflow by 8% (0.1 billion m3), with the largest decrease occurring in the 2000s. Model estimates also suggest that SWCE has greater impacts than vegetation recovery. Our study provides a useful tool for SWC planning and management in this region

Simulation of hydrological cycle in an urbanized catchment and effect evaluation of infiltration facilities

A distributed hydrological model is applied to simulate water balance in the Ebi river catchment (27km2) with a grid size of 50m and a time step of 1 hour. The simulation of 5 years from 1992 to 1996 is performed. The model is verified through comparisons of simulated river discharges and groundwater levels with the observed values. The comparison of water balance at present (1993) with that in future (2035) is also conducted and it shows the impact of urbanization. To conserve hydrological cycle in the catchment implementation of infiltration facilities is thought to be highly required. The effect of infiltration trench is studied. It is found that the hydrological cycle can be improved at same level or even better in future than now if infiltration trench is implemented to infiltrate drainage from urban canopies

Changes in Annual, Seasonal and Monthly Climate and Its Impacts on Runoff in the Hutuo River Basin, China

Much attention has focused on the effects of precipitation (P) and temperature (T) changes on runoff (R); however, the impacts of other climatic factors need to be studied further. Moreover, the monthly and seasonal scale also need to be investigated. In this paper, we investigated the characteristics of changes in annual, seasonal, and monthly hydroclimatic variables, including R, P, T, sunshine duration (SD), relative humidity (RH), and wind speed (WS), between 1956 and 2015 in the Hutuo River basin (HTRB) using the nonparametric Mann-Kendall test, the cumulative anomaly test and the Precipitation-Runoff double cumulative curve method. Additionally, we assessed the contributions of climatic factors to changes in R in the HTRB between 1956 and 2015 using the climate elasticity method. The results indicated that significant downward trends were found for both annual and seasonal R, SD, RH, and WS. In contrast, there was a nonsignificant decrease in annual P; specifically, P significantly increased in spring and winter, but P insignificantly decreased in summer and autumn. Annual and seasonal T increased significantly. The annual R showed an abrupt change in 1979; thus, the entire study period from 1956 to 2015 was divided into two periods: the baseline period (i.e., 1956–1978) and the change period (i.e., 1979–2015). The elasticities in the climatic factors were calculated using the climate elasticity method, and the elasticity values of P, T, SD, RH, and WS were 1.84, −1.07, −2.79, 1.73, and −0.45, respectively. Increasing T was the main cause of the decline in R, and decreasing SD had a large negative contribution to the decline in R in the HTRB. This study will help researchers understand the interactions between climate change and hydrological processes at the basin scale and promote water resource management and watershed planning