Understand Ephemeral Gully Mechanics and Develop Large Scale Decision Support Systems for Improved Watershed Management

非点源污染，特别是农田的泥沙和磷径流严重损害了世界各地的几种水体。近十年来，伊利湖（五大湖之一）受到严重威胁，因为有害污染物水平增加，特别是沉积物结合的磷。2011年，伊利湖的磷诱导藻华非常高，2015年夏天出现了100年来最大的藻华。预计这种退化将随着持续的人为气候和土地利用变化而恶化。******对减少沉积物和磷径流的研究更多地集中在了解薄片和细沟侵蚀过程，开发模拟这些过程的水文和水质（HWQ）模型，并使用模型来调查与政策相关的问题。仅在最近十年，短暂沟壑（EGs）被确定为一个主要来源，研究表明它们比片状和细沟侵蚀贡献更大。EGs是土壤侵蚀的局部区域，它作为小通道将细沉积物和磷从高地农田转移到河流通道。在过去几年中，人们正在努力研究耕作作业（初夏）产生的EGs，并将其作为子例程纳入少数HWQ模型。这些开发的子程序只能模拟EG侵蚀，而不能模拟磷径流。此外，在北纬地区（加拿大），EGs不仅在初夏（耕作后）形成，而且在春末由于融雪过程也会形成。******我的研究计划，在未来五年内，将推进对EG动力学（如形成，形态）和运输机制（如沉积物和磷径流）背后的科学的理解。此外，还将建立一个能够在不同时空尺度下识别EGs和估算所有气候/季节条件下沉积物和磷径流的新模型。开发的模型将与广泛使用的水土评估工具（SWAT）相结合，并将开发一个基于网络的综合决策支持系统（IWBDSS）。IWBDSS将应用于伊利湖流域，以支持各种流域规划、经济和政策分析，最终帮助安大略省政府实现到2025年将进入伊利湖的磷减少40%的愿景。开发的模型和决策支持系统也可以应用于加拿大或世界各地的任何流域，以做出更好的综合流域管理决策。最重要的是，我的研究计划将培养下一代工程师/研究人员精通现场实验和使用/开发HWQ模型，并能够在不断变化的土地利用和气候下为新兴和未来的水量和质量问题提供工程解决方案。

Non-point source pollution especially sediment and phosphorus runoff from agricultural fields are severely impairing several water bodies across the world. In the recent decade, Lake Erie (one of the Great Lakes) is under serious threat due to increased levels of harmful pollutants especially sediment-bound phosphorus. In 2011, the phosphorus-induced algae blooms in Lake Erie were exceedingly high and the summer of 2015 produced the largest algae bloom in 100 years. This degradation is projected to worsen with continued anthropogenic climate and landuse change. ******The research towards reducing the sediment and phosphorus runoff is focused more towards understanding sheet and rill erosion processes, develop Hydrologic and Water Quality (HWQ) models that simulate these processes and use models to investigate policy relevant issues. Only in the recent decade, Ephemeral Gullies (EGs) are identified as a major source and studies have shown that they contribute more than sheet and rill erosion. EGs are localized areas of soil erosion that act as small channels that transfer fine sediment and phosphorus from upland agricultural fields to stream channels. In the last few years, efforts are being made to study EGs resulting from tillage operations (early summer) and are being included as sub-routines in few HWQ models. These developed sub-routines can only simulate EG erosion but not phosphorus runoff. Furthermore, in northern latitudes (Canada), the EGs form not only during early summer (after tillage) but also during late spring as a result of snowmelt processes.******My research program, in the next five years, will advance the understanding of the science behind EG dynamics (e.g. formation, morphology) and the transport mechanisms (e.g. sediment and phosphorus runoff). Furthermore, a novel model capable of identifying EGs and also estimating sediment and phosphorus runoff in all climatic/seasonal conditions under different spatial and temporal scales will be developed. The developed model will be coupled into widely used Soil and Water Assessment Tool (SWAT) and an integrated web-based decision support system (IWBDSS) will be developed. IWBDSS will be applied in watersheds contributing to Lake Erie to support a wide variety of watershed planning, economic and policy analysis and ultimately help Ontario's government vision to reduce 40% phosphorus entering Lake Erie by 2025. The models and decision support systems developed can also be applied in any watershed across Canada or in the world to make better integrated watershed management decisions. Most importantly, my research program will produce next generation engineers/researchers proficient in both field experimentation and usage/development of HWQ models and capable of providing engineered solutions to emerging and future water quantity and quality issues under changing landuse and climate.