Yi-Chen E. Yang

Indus Basin of Pakistan : Impacts of Climate Risks on Water and Agriculture

This study, Indus basin of Pakistan: the impacts of climate risks on water and agriculture was undertaken at a pivotal time in the region. The weak summer monsoon in 2009 created drought conditions throughout the country. This followed an already tenuous situation for many rural households faced with high fuel and fertilizer costs and the impacts of rising global food prices. Then catastrophic monsoon flooding in 2010 affected over 20 million people, devastating their housing, infrastructure, and crops. Damages from this single flood event were estimated at US dollar 10 billion, half of which were losses in the agriculture sector. Notwithstanding the debate as to whether these observed extremes are evidence of climate change, an investigation is needed regarding the extent to which the country is resilient to these shocks. It is thus timely, if not critical, to focus on climate risks for water, agriculture, and food security in the Indus basin of Pakistan.

Assessing groundwater policy with coupled economic-groundwater hydrologic modeling

This study explores groundwater management policies and the effect of modeling assumptions on the projected performance of those policies. The study compares an optimal economic allocation for groundwater use subject to streamflow constraints, achieved by a central planner with perfect foresight, with a uniform tax on groundwater use and a uniform quota on groundwater use. The policies are compared with two modeling approaches, the Optimal Control Model (OCM) and the Multi-Agent System Simulation (MASS). The economic decision models are coupled with a physically based representation of the aquifer using a calibrated MODFLOW groundwater model. The results indicate that uniformly applied policies perform poorly when simulated with more realistic, heterogeneous, myopic, and self-interested agents. In particular, the effects of the physical heterogeneity of the basin and the agents undercut the perceived benefits of policy instruments assessed with simple, single-cell groundwater modeling. This study demonstrates the results of coupling realistic hydrogeology and human behavior models to assess groundwater management policies. The Republican River Basin, which overlies a portion of the Ogallala aquifer in the High Plains of the United States, is used as a case study for this analysis.

Decentralized Optimization Method for Water Allocation Management in the Yellow River Basin

The management of large river basins, such as the Yellow River Basin (YRB) in China, is complicated by distributed, localized decision processes and by mechanisms that coordinate local decisions and manage basin-level issues. Since 1998, the Yellow River Conservancy Commission (YRCC) has launched the Unified Water Flow Regulation (UWFR) as a centralized controlling mechanism that enforces an upper limit on water withdrawals (water use permits) for eight provinces located in the basin. The implementation of UWFR has maintained a prescribed minimum flow in the downstream channel and avoided the flow cutoff events that occurred every year between 1972 and 1998. This study attempts to explore the socioeconomic and environmental consequences of the regulation and test plans to improve water allocation management in the YRB. A decentralized optimization is combined with a multipleagent system (MAS) framework for the YRB, in which water users, reservoirs, and downstream ecological zones are defined as agents. This method iteratively determines water prices for each water use agent in the context of water market. The proposed water market scenario shows possible improvements of UWFR with respect to social, economic, and environmental objectives. DOI: 10.1061/(ASCE)WR.1943-5452.0000199.

Reservoir Reoperation for Fish Ecosystem Restoration Using Daily Inflows—Case Study of Lake Shelbyville

Ecosystem restoration calls for reservoir reoperation. Traditionally, a minimum water release is set as a constraint for downstream ecosystem flow requirement. Recently, research has been conducted for the purpose of recovering natural flow regimes to a practical degree. This paper examines the practicality of adding an ecological objective to the operation of Lake Shelbyville, a reservoir situated on the Kaskaskia River in east central Illinois, which has been used primarily for flood control. A multiobjective optimization model that minimizes flood damage (the dominating priority in the historical operation) and maximizes fish diversity for the downstream ecosystem is developed for daily operation of the reservoir. The challenges addressed in this paper include handling daily reservoir release for the ecological assessment and evaluating the practicality of changing the existing operation rules for the purpose of including an ecological objective. The model results in the reduction of the maximum allowa...

An introduction to the IBMR, a hydro-economic model for climate change impact assessment in Pakistan's Indus River basin

The Indus Basin Model Revised (IBMR) is a hydro-agro-economic optimization model for agricultural investment planning across Pakistan’s Indus Basin provinces. This study describes IBMR-2012, an update and modification of the model that reflects the current agro-economic conditions in Pakistan for the purpose of evaluating the impact of climate change on water allocation and food security. Results of hydro-climatic parameter sensitivity and basin-wide and provincial-level climate change impacts on crop productions are presented. The study finds that compared to Punjab, Sindh faces both significantly larger climate change impacts on agriculture and higher uncertainty regarding climate change impacts in the future.

Application of genetic programming to project climate change impacts on the population of Formosan Landlocked Salmon

This work presents a novel methodology, genetic programming (GP), for developing environmental response functions for Formosan Landlocked Salmon (Oncorhynchus masou formosanus); these functions are then applied to evaluate the impacts of climate changes. Average daily temperature and maximal flows between two sampling periods were adopted as principal factors for categorizing environmental conditions. The GP successfully identified the response functions for various environmental categories. The response functions were further applied to assess the impact of climate change. Fourteen future possible climate scenarios were derived based on the equilibrium and transition experiments by GCMs. Impact assessment results indicated that climate change may significantly influence populations of Formosan Landlocked Salmon due to more frequent higher temperatures. Adaptation strategies are required to mitigate the impact of global climate change as current conservation measures for Formosan Landlocked Salmon habitat only reduce local human-induced effects. In the situation of complicated relationships between fish population and environmental conditions, GP provides a useful tool to obtain some information from the limited data.

Combining regression and spatial proximity for catchment model regionalization: a comparative study

Abstract Spatial error regression is employed to regionalize the parameters of a rainfall–runoff model. The approach combines regression on physiographic watershed characteristics with a spatial proximity technique that describes the spatial dependence of model parameters. The methodology is tested for the monthly abcd model at a network of gauges in southeast United States and compared against simpler regression and spatial proximity approaches. Unlike other comparative regionalization studies that only evaluate the skill of regionalized streamflow predictions in ungauged catchments, this study also examines the fit between regionalized parameters and their optimal (i.e. calibrated) values. Interestingly, the spatial error model produces parameter estimates that better resemble the optimal parameters than either of the simpler methods, but the spatial proximity method still yields better hydrologic simulations. The analysis suggests that the superior streamflow predictions of spatial proximity result from its ability to better preserve correlations between compensatory hydrological parameters. Editor D. Koutsoyiannis; Associate editor Y. Gyasi-Agyei

Groundwater Resource Planning to Preserve Streamflow: Where Environmental Amenity Meets Economic Welfare Loss

Streams and their associated biological communities are among our most valuable natural resources. Humans rely on the environmental services provided by streams in a myriad of ways. However, in some areas, excessive groundwater pumping exacerbates the already critical pressure on streamflow and must be managed through effective planning. Based on economic and hydrogeological concepts, this study estimates the quantity of streamflow depletion that is attributable to groundwater pumping and the negative impact on the socioeconomic system if groundwater pumping must be constrained to restore streamflow. The primary objective of this paper is to develop a multiobjective nonlinear optimization model to simulate the tradeoffs between streamflow restoration and economic welfare loss in a Chicago suburban county, McHenry County. The multiobjective optimization was conducted at both county and municipality levels. An evolutionary algorithm, the nondominated sorting genetic algorithm, was used to solve the optimization model and to identify the tradeoff curve (Pareto frontier). Comparing municipal Pareto frontiers shows spatially heterogeneous costs of preserving streamflow through various shadow prices and also the different capacities of restoring streamflow. The results include discussion of the shapes of the Pareto frontier, the sensitivity of the pumping boundary constraints, and return flow coefficients. It is concluded that the multiobjective optimization model provides a useful framework to consider conflicting objectives in a typical environmental management and planning process, and that the findings can help decision-makers and planners to formulate effective groundwater pumping strategies. DOI: 10.1061/(ASCE)WR .1943-5452.0000269.

The Effect of Groundwater Allocation on Economic Welfare Loss

Water scarcity has become a constraint for regional economic development in many cities and regions. Water rationing serves as one instrument to constrain water consumption to persuade users to save water and to moderate their consumption. When the supply of water is unable to satisfy demand, a loss of welfare for the water users will usually occur. This paper conducts an empirical case study on a Chicago suburban county, McHenry County, to evaluate effective water allocation strategies under possible water scarcity scenarios, by specifically taking into consideration of the economic welfare loss under water rationing. It points out the inefficiency of equal rationing and tests a more effective optimal rationing regime which could significantly lower the overall welfare loss for McHenry County. Instead of a conventional watershed-based approach that would provide little advantage for an area that mostly relies on groundwater, this study adopts regional planning/political boundaries as its spatial analytical units. The outcomes suggest that municipality-level water resources management models, powered under economic welfare objective functions, are both possible and practical. The planning strategy drawn under such optimization models suggests a variety of promising approaches to manage groundwater resources at county scales.

Understanding Hydrological Cycle Dynamics Due to Changing Land Use and Land Cover: Congo Basin Case Study

Land use and land cover changes (LULCC) significantly modify the hydrological flow regime of the watersheds, affecting water resources and environment from regional to global scale. In recent years, with an increased number of launched satellites, regular updates of land-cover databases are available. This study seeks to advance and integrate water and energy cycle observation, scientific understanding, and its prediction to enable society to cope with future climate adversities due to LULCC. We use the Common Land Model [1] which is developed with enhanced spatial and temporal resolution, physical complexity, hydrologic theory and processes to quantify the impact of LULCC on hydrological cycle dynamics. A consistent global GIS-based dataset is constructed for the surface boundary conditions of the model from existing observational datasets available in various resolutions, map projections and data formats. Incorporation of the projected LULCC of Intergovernmental Panel on Climate Change (IPCC) A1B scenario [2] into our hydrologic model enhances scientific understanding of LULCC impact on the seasonal hydrological dynamics. An interesting case study is addressed over the Congo basin located in the western central Africa which has the second largest rain forest area in the world. It is surrounded by plateaus merging into savannas in the south, mountainous terraces and grassland in the west and mountainous glaciers in the east. Savanna and Evergreen Broadleaf forest are projected to be cleared off in places to be replaced by dryland, cropland and pasture.