Yield,water use efficiency and economic analysis of energy sorghum in South Texas

Yields, water use efficiency and economic returns (net farm revenues) of biomass sorghum [Sorghum bicolor (L.) Moench] were investigated over two years (2012 and 2014) under limited water resource conditions. Energy sorghum was grown under four water supply regimes: rain-fed (or dry-land, level 1), 50% (level 2), 75% (level 3) and 100% (level 4) of crop evapotranspiration rates (% ET_c). Biomass yields ranged from 5.8 to 16.6 Mg ha⁻¹ (dry weight) after 126 days of growth. Average water use efficiencies ranged from 3.95 kg m⁻³ to 23.4 kg m⁻³. Net return was approximately 410 $ ha⁻¹ with water depths above 400 ha-mm. These results suggest that it is possible to obtain more than 60 Mg ha⁻¹ of sorghum biomass (wet basis) with at least 425 mm of water. While biomass yield under irrigation was greater than rain-fed conditions, there were no significant differences among irrigation treatments. Biomass chemical composition did not differ significantly among water treatments suggesting that biofuel quality would not be affected by water deficits.     

Economic and environmental assessment of irrigation water policies: A bioeconomic simulation study

We present a bioeconomic modeling approach that links the biophysical crop growth model CropSyst to an economic decision model at field scale. The developed model is used in conjunction with a genetic algorithm to optimize management decisions in potato production in the Broye catchment (Switzerland) in the context of different irrigation policy scenarios. More specifically, we consider the effects of water bans, water quotas, and water prices on water consumption, profitability, and the financial risks of potato production. The use of a genetic algorithm enables the direct integration of the considered decision variables as management input factors in CropSyst. We employ the farmer's certainty equivalent, measured as the expected profit margin minus a risk premium, as the objective function. Using this methodological framework allows us to consider the potential impacts of policy measures on farmers' crop management decisions due to their effects on both expected income levels and income variability.Our results show that the region's current water policy, which frequently prevents irrigation during hot and dry periods by banning water withdrawal, causes high levels of income risk for the farmer and increases the average water demand in potato production. In contrast, the implementation of an appropriate water quota could significantly decrease water consumption in potato production while allowing the farmer's certainty equivalent to remain at the same level as it is under the current irrigation water policy.     

基于GIS的玛纳斯河灌区信息系统设计与应用

为进一步提高水资源利用的效率和灌区管理水平，本文针对玛纳斯灌区的实际情况，提出空间信息与灌区业务管理信息有机融合的理念，依据业务管理需求，设计了灌区信息系统的体系结构并定义了系统功能。在对灌区的量测水方法进行研究的基础上，玛纳斯灌区信息系统实现了灌区信息管理中的监测监控、量水测水、配水调度、水费计收以及防汛和工程运行管理等业务工作的自动化和智能化。     

Explicit solution for normal depth of parabolic section of open channels

To obtain the normal depth of parabolic section of open channels, multiple known parameters were incorporated into a comprehensive one by transforming basic equations, and a concept of the non-dimensional normal depth was introduced. The normal depth equations were simplified into a non-dimensional iterative formula that was proved to have a high velocity of convergence. By analyzing the comprehensive parameter and dimensionless normal depth under condition of usually adopted sizes of parabolic channels and through establishing their relationship, the iterative initial value of normal depth was obtained. The normal depth of parabolic channels was acquired by substituting the initial value into the iteration formula. The error analysis was made and a case study was provided as an application example. The case study showed that the iteration formula was very simple, convenient and precise for determining the normal depth of parabolic channels with the maximum relative error of normal depth being less than 0.34% when the ratio of width to depth was between 0.2 and 20.     

Targeting investments in small-scale groundwater irrigation using Bayesian networks for a data-scarce river basin in Sub-Saharan Africa

Irrigation for smallholder farming systems is an important approach for sustainable intensification and increased productivity in Sub-Saharan Africa, provided investments in irrigation are properly targeted and accompanied by complementary improvements. Many GIS-based tools have been developed to identify suitable areas for investments in different types of small scale irrigation (SSI), but they do not explicitly address uncertainty on the data input and on the determination of factors that affect success of an investment in a given context. This paper addresses this problem by presenting an application of a decision-support targeting tool based on Bayesian networks (BNs) that can be used by non-expert policy-makers and investors to assess the potential success of specific technologies used for groundwater-based SSI. A case study application for the White Volta Basin in West Africa is presented to illustrate the BN approach.     

Framework for computationally efficient optimal crop and water allocation using ant colony optimization

A general optimization framework is introduced with the overall goal of reducing search space size and increasing the computational efficiency of evolutionary algorithm application to optimal crop and water allocation. The framework achieves this goal by representing the problem in the form of a decision tree, including dynamic decision variable option (DDVO) adjustment during the optimization process and using ant colony optimization (ACO) as the optimization engine. A case study from literature is considered to evaluate the utility of the framework. The results indicate that the proposed ACO-DDVO approach is able to find better solutions than those previously identified using linear programming. Furthermore, ACO-DDVO consistently outperforms an ACO algorithm using static decision variable options and penalty functions in terms of solution quality and computational efficiency. The considerable reduction in computational effort achieved by ACO-DDVO should be a major advantage in the optimization of real-world problems using complex crop simulation models.     

Hydraulic bureaucracies and Irrigation Management Transfer in Uzbekistan: the case of Samarkand Province

Since the 1990s, Irrigation Management Transfer has been considered the world over to be a policy aimed at rolling back state influence in water management according to a neo-liberal approach. The initiative was endorsed by international organizations as a way of reforming the water sector in developing countries. Reflecting on this process, the role of hydraulic bureaucracies in driving reforms oriented towards IMT has often been neglected in academic debate. This article discusses the logic of IMT implementation and the establishment of Water Users' Associations (WUAs) in Uzbekistan, specifically in Samarkand province. These dynamics have been analysed over the last 10 years showing different trajectories within Uzbekistan. Data were collected through extensive fieldwork in three districts in Samarkand province. The evidence acquired shows that, on the one hand, WUAs were established to be a new structure for state control over water and agriculture, in conflict with IMT rationale, and, on the other, that WUAs were created in the province as a result of a local initiative promoted by the hydraulic bureaucracy and accepted by the national authorities due to influential power relations.     

Recursive Design of Pressurized Branched Irrigation Networks

This paper presents a new method to design pressurized branched irrigation networks. This method is called recursive design and is based on application of the problem-solving technique known as backtracking to the problem of the optimum design of pressurized branched irrigation networks with a known delivery piezometric head (pipe-sizing). Recursive design is a heuristic optimizer, like genetic algorithms, and has been implemented in a fast, versatile computer application. After presenting and precisely defining the design problem, the writers review the theoretical foundations of some of the main existing design methods: maximum velocity, recommended velocity, Mougnie velocity, constant hydraulic slope, Lagrange multipliers, linear programming, Labye’s method, and genetic algorithms. Next, the writers explain what recursive design consists of and apply its methodology in detail to a simple network. In the results section, the solutions obtained by recursive design are compared with those obtained by the other design methods, giving satisfactory results. For example, in an analyzed standard network, genetic algorithms take more than 20?minutes to offer a solution, whereas recursive design offers a cheaper solution with less than 3?seconds of computation time.     

Root Zone Moisture Routing and Water Demand Calculations in the Context of Integrated Hydrology

An important issue that integrated hydrologic models (IHMs) for river basins can address is the management of water resources in heavily inhabited and cultivated basins. To address this issue, these models need to simulate water demands and root zone flows in a basin. Irrigation scheduling models (ISMs) have been widely used by professionals to compute farm level water demands and root zone flows. Available ISMs are neither suitable for use at basin scale nor can they be easily linked to IHMs. This paper describes a new model that utilizes methods used by ISMs to compute root zone flows and water demands in river basins and can be linked to IHMs. The model was applied to a basin in California, and the simulated water demands were compared with data compiled for the basin. The differences in the results were attributed to differences in input potential evapotranspiration rates. The paper demonstrates that simulated water demands for rice are very sensitive to saturated soil hydraulic conductivity, whereas demands for other crops are sensitive to the pore size distribution index.     

Influence of Regulators in Controlling Upstream Water Depth

Control of irrigation canals usually consists of control of water levels upstream from regulators or check structures. Regulators provide the necessary head to offtakes. Generally, influence factor is used to express the extension of the backwater curve effect within the controlled reach. This factor shows how a change in water depth exercised by a regulator can influence the water surface profile along an irrigation canal. No direct equation is available in the technical literature up until now for calculating this factor on the basis of the steady gradually varied flow theorem. In current research, using the steady gradually varied flow equation for a prismatic canal, an elegant algebraic equation for this factor is derived. Control of water levels upstream from regulators is an important application of this equation in irrigation networks.