Chinese water policy for sustainable water resources: Options for the future

China has no option but to press on with the implementation of the National Water Initiative as stated by its government in ‘’Document No. 1". One might observe that it can be a bit heavy in political terms. Most hydrological means are pretty meaningless in reality. Though the nation is not sure if it can handle such a project effectively yet, it will certainly approach it with a degree of commitment. The paper aims to build an integrated understanding of these issues and to illustrate appropriate policy directions and management practices. These are ambitious goals, but they are essential and relevant in the milestone of the Chinese water resources management and policy.Key words: Climate change, Chinese water vision, the national water initiative, national water resources management, integrated water resources management, policy implications

Impacts of Climate Variability and Human Activities on the Changes of Runoff and Sediment Load in a Catchment of the Loess Plateau, China

The objectives of this study are to investigate the changes of runoff and sediment load and their potential influencing factors in the Huangfuchuan catchment. The Mann-Kendall test and accumulative anomaly methods were, respectively, applied to examine the changing trends and abrupt changes. Both annual runoff and sediment load demonstrated significant reduction (p<0.05) with decreasing rates of −3.2 × 106 m3/a and −1.09 Mt/a, respectively. The abrupt changes were detected in 1979 and 1996 for the runoff and sediment load. All the runoff and sediment indices (runoff, sediment load, runoff coefficient, and sediment concentration) exhibited remarkable reduction (p<0.01). The climate variability contributed 24.4% and 25.1% during 1980–1996 and 1997–2010 to annual runoff decrease, respectively, and human activities accounted for the remaining 75.6% and 74.9%. In contrast, changes in precipitation accounted for 43.5% and 20.2% of sediment load reduction during 1980–1996 and 1997–2010, whereas the human activities contributed 56.5% and 79.8%, respectively. The relative contributions from climate variability and human activities to runoff and sediment load changes at annual scale were different from that at flood season scale. Results suggested the dominant role of soil and water conservations in the variation of runoff and sediment load in the catchment

Effects of Thinning Intensities on Soil Infiltration and Water Storage Capacity in a Chinese Pine-Oak Mixed Forest

Thinning is a crucial practice in the forest ecosystem management. The soil infiltration rate and water storage capacity of pine-oak mixed forest under three different thinning intensity treatments (15%, 30%, and 60%) were studied in Qinling Mountains of China. The thinning operations had a significant influence on soil infiltration rate and water storage capacity. The soil infiltration rate and water storage capacity in different thinning treatments followed the order of control (nonthinning): <60%, <15%, and <30%. It demonstrated that thinning operation with 30% intensity can substantially improve soil infiltration rate and water storage capacity of pine-oak mixed forest in Qinling Mountains. The soil initial infiltration rate, stable infiltration rate, and average infiltration rate in thinning 30% treatment were significantly increased by 21.1%, 104.6%, and 60.9%, compared with the control. The soil maximal water storage capacity and noncapillary water storage capacity in thinning 30% treatment were significantly improved by 20.1% and 34.3% in contrast to the control. The soil infiltration rate and water storage capacity were significantly higher in the surface layer (0~20 cm) than in the deep layers (20~40 cm and 40~60 cm). We found that the soil property was closely related to soil infiltration rate and water storage capacity

Variation of Runoff and Precipitation in the Hekou-Longmen Region of the Yellow River Based on Elasticity Analysis

Precipitation is very important to the formation of runoff, and studying of runoff variation and its response to precipitation has practical significance to sustainable utilization of water resources. The study used Mann-Kendall test, anomaly accumulation method, and precipitation elasticity of runoff method to analyze the changes in the relation of precipitation and runoff and the contribution of precipitation to runoff change in the Hekou-Longmen region (from 1957 to 2010), Huangfuchuan watershed (from 1954 to 2010), and Yanhe watershed (from 1952 to 2010) in the middle reaches of the Yellow River. The results showed that runoff appeared a significant decreasing trend (P=0.01) while it was not significant in precipitation in all study areas. In particular, the reductions of average annual runoff in the Hekou-Longmen region, Huangfuchuan watershed, and Yanhe watershed were 72.7%, 87.5%, and 32.2%, respectively, during 2000–2010 compared to the 1950s. There existed two abrupt change points of the runoff in the Hekou-Longmen region and Huangfuchuan watershed, which were detected in 1979 and 1998. But in the Yanhe watershed only one abrupt change point was found in 1996. The precipitation elasticities of runoff were 1.11, 1.09, and 1.26, respectively, and the contributions of precipitation on runoff reduction were 26.4%, 17.9%, and 31.6%, respectively, in the Hekou-Longmen region, Huangfuchuan watershed, and Yanhe watershed

Comparison of soil erosion models used to study the Chinese Loess Plateau

The Loess Plateau suffers from severe soil erosion that leads to a series of ecological and economic problems such as reduced land productivity, exacerbated rural poverty, decreased biodiversity and sedimentation of the riverbed in the lower reaches of the Yellow River. Soil erosion models are commonly used on the Loess Plateau to help target sustainable land management strategies to control soil erosion. In this study, we compared eleven soil erosion models that were previously used on the Loess Plateau. We studied their prediction accuracy, process representation, data and calibration requirements, and potential application in scenario studies. The selected models consisted of a broad range of model types, structures and scales. The comparison showed that process-based and empirical models did not necessarily yield more accurate results over one another for the Loess Plateau. Among the process-based models, Si’ model, WEPP and MMF had the highest prediction accuracy. However, some of the selected models were tested with total sediment load while others were tested with suspended sediment load (i.e. bedload is not included), which is subject to several drawbacks. Research questions that each of the models can address on the Loess Plateau were suggested. Further improvement of soil erosion models for the Loess Plateau should concentrate on enhancing the quality of data for model implementation and testing, incorporating key processes into process-based models according to their aims and scales, comparing models that address the same research questions, and implementing internal and spatial model testing

Erosion of Northern Hemisphere blanket peatlands under 21st-century climate change

Peatlands are important terrestrial carbon stores particularly in the Northern Hemisphere. Many peatlands, such as those in the British Isles, Sweden and Canada, have undergone increased erosion, resulting in degraded water quality and depleted soil carbon stocks. It is unclear how climate change may impact future peat erosion. Here we use a physically-based erosion model (PESERA-PEAT), driven by seven different global climate models (GCMs), to predict fluvial blanket peat erosion in the Northern Hemisphere under 21st-century climate change. After an initial decline, total hemispheric blanket peat erosion rates are found to increase during 2070-2099 (2080s) compared with the baseline period (1961-1990) for most of the GCMs. Regional erosion variability is high with changes to baseline ranging between -1.27 and +21.63 t ha-1 yr-1 in the 2080s. These responses are driven by effects of temperature (generally more dominant) and precipitation change on weathering processes. Low latitude and warm blanket peatlands are at most risk to fluvial erosion under 21st-century climate change

Spatial variability of fluvial blanket peat erosion rates for the 21st Century modelled using PESERA-PEAT

Many peatlands across the world suffer from degradation. Blanket peatlands are found mainly in high latitude oceanic areas and subpolar islands. Exacerbated erosion of blanket peatlands is common particularly where they have been disturbed by human influence or where climate has become more marginal for their functioning. A recently developed fluvial blanket peat erosion model, PESERA-PEAT was applied across 845 km2 of blanket peatlands in the North Pennines of northern England. The aim was to evaluate the spatial and temporal variability of erosion rates under climate change and land management scenarios. Climate change data to the end of the 21st Century, derived from UKCP09 median emission projections aligned to the UK Met Office’s historical meteorological dataset, were downscaled to 100 m cells. Land management scenarios were developed which included intensified and extensified grazing, artificial drainage and prescribed burning. The modelling results showed that under current management, 21st Century climate change would slightly increase the overall fluvial erosion rates for the study region from the climatic baseline (2.2 t ha-1 yr-1) to the 2080s (2.3 t ha-1 yr-1 ). However, the predicted response to climate change was spatially very variable. Predicted erosion rates decreased at locations that are currently wet and cold while they increased in some warmer and drier locations by more than 50%. Summer desiccation was found to become more important for the study region under climate change. Thus, predicted autumn sediment yields became the biggest component of the annual budget by the 2080s. Less intensive management was shown to reduce blanket peat erosion but potentially enhance wildfire severity. The results demonstrated that land management change will be useful in mitigating the impact of 21st Century climate change on the amount and spatial pattern of blanket peat erosion. The results of our study can be used within blanket peatland regions to inform spatially-targeted management strategies