1. Liu, Y.B., Yang, W., Qin, C., and Zhu, A., 2016. A review and discussion on modeling and assessing agricultural best management practices under global climate change. Journal of Sustainable Development 9(1): 245-255.
Understanding the impacts of global climate change on the spatiotemporal pattern of hydrologic cycle and water resources is of major importance in highly developed watersheds all over the world. These impacts are strongly dependent on related changes in intensity and frequency of extreme climate events. Implementation of Best Management Practices (BMPs) and policy approaches at watershed and regional scales is essential for mitigating their negative impacts on soil and water conservation, and sustainable economic development. However, the uncertainty of BMP effectiveness including increasing variability of future water supply and changing magnitudes of nonpoint source pollution has to be accounted for in watershed planning and management. This paper provides a review and discussion on the impacts of global climate change on BMP’s hydrologic performance, the current progress on hydrologic assessment of BMPs, as well as the existing problems and countermeasures. Research challenges and opportunities in the field of hydrologic assessment of BMPs under global climate change are also discussed in this paper.
2. Yang, W., Liu, Y.B., Ou, C., and Gabor, S. 2016. Examining water quality effects of riparian wetland loss and restoration scenarios in a southern Ontario watershed. Journal of Environmental Management 174: 26-34.
Wetland conservation has two important tasks: The first is to halt wetland loss and the second is to conduct wetland restoration. In order to facilitate these tasks, it is important to understand the environmental degradation from wetland loss and the environmental benefits from wetland restoration. The purpose of the study is to develop SWAT based wetland modelling to examine water quality effects of riparian wetland loss and restoration scenarios in the 323-km2 Black River watershed in southern Ontario, Canada. The SWAT based wetland modelling was set up, calibrated and validated to fit into watershed conditions. The modelling was then applied to evaluate various scenarios of wetland loss from existing 7590 ha of riparian wetlands (baseline scenario) to 100% loss, and wetland restoration up to the year 1800 condition with 11,237 ha of riparian wetlands (100% restoration). The modelling was further applied to examine 100% riparian wetland loss and restoration in three subareas of the watershed to understand spatial pattern of water quality effects. Modelling results show that in comparing to baseline condition, the sediment, total nitrogen (TN), and total phosphorus (TP) loadings increase by 251.0%, 260.5%, and 890.9% respectively for 100% riparian wetland loss, and decrease by 34.5%, 28.3%, and 37.0% respectively for 100% riparian wetland restoration. Modelling results also show that as riparian wetland loss increases, the corresponding environmental degradation worsens at accelerated rates. In contrast, as riparian wetland restoration increases, the environmental benefits improve but at decelerated rates. Particularly, the water quality effects of riparian wetland loss or restoration show considerable spatial variations. The watershed wetland modelling contributes to inform decisions on riparian wetland conservation or restoration at different rates. The results further demonstrate the importance of targeting priority areas for stopping riparian wetland loss and initiating riparian wetland restoration based on scientific understanding of watershed wetland effects.
3. Yang, W., Liu, Y.B., Cutlac, M., Boxall, P., Weber, M., Bonnycastle, A. and Gabor, S. 2016. Integrated economic-hydrologic modeling for examining cost-effectiveness of wetland restoration scenarios in a Canadian prairie watershed. Wetlands 36:577–589.
This study develops an integrated economic-hydrologic modeling to examine cost effectiveness of wetland restoration scenarios in the 75-km2 South Tobacco Creek watershed in the Canadian prairie region. The modeling results show that spatial variations of wetland restoration costs are driven by forgone cropping returns while wetland restoration benefits in terms of total phosphorus (TP) reductions are related to wetland drainage area characteristics including slope, soil, and land use, and wetland features such as size, volume, and position relative to the stream network. For a TP reduction goal of 141.1 kg/yr or 4.3%at the watershed outlet, the spatial targeting scenario based on economic cost to environmental benefit ratios identifies 28.8 ha of wetland restoration costing $3,058.6/yr. The cost ceiling scenario based on minimizing economic costs only would have to restore 80.1 ha of wetlands costing $8,032.6/yr. In comparison, the cost ceiling scenario requires 178.2 % more wetland restoration areas and would cost 162.6 % more than those of the spatial targeting scenario. The study contributes to develop integrated economic-hydrologic modeling to inform wetland restoration decision at farm field scale. The modeling results demonstrate the importance of spatially targeting wetland restoration based on economic cost to environmental benefit ratios in order to achieve cost-effectiveness.
4. Yang, W., Liu, W., Liu, Y.B, Corry, R.C., Kreutzwiser, R.D. 2014. Cost-effective targeting of riparian buffers to achieve water quality and wildlife habitat benefits. International Journal of River Basin Management 12 (1): 43-55.
This study develops an integrated economic, hydrologic, and ecological modelling framework to examine cost-effective targeting of riparian buffers to achieve water quality and wildlife habitat benefits. The framework is empirically applied to the Canagagigue Creek watershed in Ontario, Canada to compare the economic costs for establishing riparian buffers under three alternative environmental and ecological constraints: sediment abatement only, habitat improvement only, and riparian buffer acreage only. The results show that riparian buffers targeted for achieving sediment abatement goal are not effective in improving habitat quality. Similarly, riparian buffers identified through habitat improvement goal achieve less sediment abatement as compared to those targeted in the sediment abatement scenario. The trade-offs suggest that agricultural stewardship programmes with joint water quality and habitat improvement goals may need to allocate funds independently for targeting two pools of riparian buffers: for improving water quality only or for improving habitat only.
5. Liu, Y.B., Yang, W., Yu, Z., Lung, I., & Yarotski, J. 2014. Assessing the effects of small dams on stream flow and water quality in an agricultural watershed. Journal of Hydrologic Engineering 19(10), 05014015.
Small dams and associated reservoirs have notable effects on soil and water dynamics in prairie streams. In this study, we developed a simulation module of small dams in the soil and water assessment tool (SWAT) to evaluate their long-term effects on stream flow and water quality at a watershed scale. To overcome the challenges in characterizing small storage and short retention time in small reservoir routing, concepts of equivalent reservoir storage and equivalent reservoir discharge are applied by which the average daily storage and daily discharge of the small reservoirs are calculated. Accordingly, the sediment deposition and nutrient abatement within the reservoir are computed using available SWAT routines. The effects of small dams in reduction of daily peak flow, sediment, and nutrient loads at the watershed outlet are obtained by summing the effects of all small dams within the watershed considering both reservoir and channel processes.
The model is applied to the 74.6-km2 South Tobacco Creek watershed located in Southern Manitoba of Canada. A total of 26 small dams exist in the watershed with surface area ranging from 0.002 to 0.492 km2 and storage capacity from 3,380 to 642,000 m3. The simulation results show that the combined effect of these small dams can reduce daily peak flow by 0–14% at the watershed outlet depending on climate and initial reservoir storage conditions. The estimated average annual sediment, total nitrogen and total phosphorus reductions at the watershed outlet are about 4.51, 3.59, and 2.96%, respectively. However, the on-site effects of individual small dams are much higher depending on its size, location, shape, drainage area, and land use compositions in the contribution area. The simulation results also show that snowmelt-flooding events have higher reduction amounts but lower relative reduction rates compared to rainfall storm events and the back-flood small dams have greater impact on sediment, nitrogen, and phosphorous abatement followed by multipurpose small dams and dry dams in the study watershed.
6. Yang, W., Bryan, B.A., MacDonald, D.H., Ward, J.R., Wells, G., Crossman, N.D., and Connor, J.D. 2010. A conservation industry for sustaining natural capital and ecosystem services in agricultural landscapes. Ecological Economics 69(4): 680–689.
Conservation investment in agricultural landscapes has evolved to take a more market-based or business approach. However, current levels of conservation investment are not likely to mitigate degradation to natural capital and ecosystem services. We propose the further evolution of a conservation industry to generate substantially increased investment in conservation in agricultural landscapes, particularly from the private sector. A mature conservation industry is envisaged as comprising of investors, producers, and service providers who produce conservation products and services, exchanged via market transactions. A number of requirements for a viable and effective conservation industry are identified including institutional infrastructure (conservation market institutions and regulatory systems), information provision (quantifying benefits, business models, and accounting and auditing standards), and facilitation (entrepreneurship incubation and capacity building). A conservation industry requires careful design and planning in order to operate effectively. Whilst it is not without risk, a conservation industry has the potential to increase participation and investment in conservation actions and enhance the sustainability of agricultural landscapes.
7. Yang, W., Rousseau, A.N. and Boxall, P. 2007. An Integrated Economic-Hydrologic Modeling Framework for the Watershed Evaluation of Beneficial Management Practices. Journal of Soil and Water Conservation 62(6): 423 – 432.
This paper develops an integrated economic-hydrologic modeling framework that includes an on-farm economic model, a farmer adoption behavior model, a watershed modeling toolbox and a nonmarket valuation economic model for watershed evaluation of beneficial management practices (BMPs). The modeling framework is specifically designed for the watershed evaluation of BMPs (WEBs) project, which was established as a partnership between Agriculture and Agri-Food Canada and Ducks Unlimited Canada in 2003. The modeling framework could be applied to examine tradeoffs between on-farm costs, pollution abatement, water quality improvement, and societal value in evaluating agricultural conservation programs. In comparison with previous studies, the modeling framework not only integrates economic and physical models but also incorporates normative and behavioral elements in addressing the complex conservation issue. This study introduces a modeling framework for policy-makers and program managers to improve the design and implementation of conservation programs to meet the environmental and ecological goals more cost-effectively.