Effect of Runoff Dynamic on Sediment and Nitrogen Losses in an Agricultural Watershed of the Southern Shaanxi Region, China

Abstract

The southern Shaanxi region will become a water source area of the middle route of the South-to-North Water Diversion Project after 2014. However, there is little knowledge of water quality conditions in the region. Therefore, 12 rainfall events were monitored to investigate the effect of runoff dynamics on sediment and nitrogen (N) losses during the 2011 rainy season in the Hougou agricultural watershed. The results showed that at the seedling stage (SS), most of the rainfall contributed to an increase in the soil water content, both runoff and sediment yield were small, and there was a significant linear correlation between runoff and sediment yield (r ¼ 0.957, p < 0.01). Despite an increase in vegetation coverage at the vigorous stage (VS), both runoff and sediment yield clearly increased with increasing rainfall, and there was a significant power function relationship between runoff and sediment yield (r ¼ 0.922, p < 0.01). In addition, there was a significant linear correlation between runoff and sediment yield (r ¼ 0.981, p < 0.01) at the harvest stage (HS). The best fit equations among N losses (N) and runoff (R), sediment yield (S) is N ¼ aR b S c , and the method proposed was available to reduce relative error for calculation of N losses during the 2011 rainy season.

Quantifying Water Pollution Sources in a Small Tile‐drained Agricultural Watershed

“…The evaluated results (especially regressions after runoff separation), showed that the pollution coming from non‐point sources (including tile drainage systems) was relatively variable for all the monitored parameters and that the solute loads were influenced predominantly by hydrology. This is in agreement with findings from similar studies . The monthly specific solute loads for all monitored subcatchments, i.e.…”

“…In general, all these phenomena depend on the ‘behaviour’ of various catchment segments in different phases of the year or during R–R events in relation to the natural, anthropogenic or ‘mixed’ factors . These factors are the weather course, land cover (land use and management, crop/tree, type and timing of agro‐technology/forest operation management), application of fertilizers, heterogeneous physical and chemical soil properties, geomorphological, hydrological and hydrogeological conditions of a watershed and land improvement interventions in various watershed zones .…”

Effectiveness of Dichanthium annulatum in Watercourses for Reducing Sediment Delivery from Agricultural Watersheds

“…Runoff and vegetative ground cover were the main factors that were responsible for the differences in sediment and nitrogen losses . The runoff dynamics and stage of crop were the main responsible factors for sediment and nitrogen losses from agricultural watersheds . It can also be observed that for <50% grass coverage treatment, irrespective of the discharge, erosion started.…”

Irrigation Water Use Efficiency Based on the Deficit Irrigation Theories

“…If the return flow were to be reused, e.g. unused water in upstream area being reused in downstream area, redundant water diversion project and secondary investment would be required [15]. Considering the commodity value of irrigation water itself and economic connotation involved in management of irrigation water, we should maximize its one-time utilization rate and minimize the costs of secondary utilization [16].…”