Performance diagnosis of Mae Lao Irrigation Scheme in Thailand (I) Development of Unsteady Irrigation Water Distribution and Consumption model

Abstract

The Mae Lao Irrigation Scheme is one of the largest irrigation projects in Northern Thailand. According to the field reconnaissance, water shortage usually occurs during the dry season. And it is very difficult to equally distribute available water to the paddy fields from the upstream to the downstream parts of the system. To understand and identify the causes of the problems, the measurement of water level and flow rate along all canals may be effective. However, it is not easy to achieve this in such a large-scale irrigation system. Thus, the numerical simulation becomes the second option. The objective of this study is to identify and quantify the real water shortage causes by developing an Unsteady Irrigation Water Distribution and Consumption model which can simulate the water movement and consumption in the whole irrigation system. The beneficial area of the right main canal is modeled based on the physical aspect of the system. The components of the model consist of canal networks, control structures, and paddy fields. A canal is divided into several portions called reach. The Saint-Venant equations are applied to describe the unsteady water movement in each reach. Flow movement at the control structure is expressed by the boundary condition. The paddy fields are modeled to make paddy block and connected to each reach. The water consumption in each paddy block is estimated by Paddy Tank model. The numerical model is successfully developed showing the ability to simulate the water movement and consumption properties in this irrigation system.

Bonding and bridging social capital towards collective action in participatory irrigation management. Evidence in Chiang Rai Province, Northern Thailand

“…The study uses the case of water users in the Mae Lao Irrigation Project (MLIP) located in Chiang Rai, Northern Thailand. The MLIP is one of the RID’s largest irrigation projects covering 29,440 hectares (Wongtragoon et al , 2009). The Mae Lao River originates in the Phi Pan Nam Range.…”

“…Group members execute farming activities per irrigation schedule and provide crop pattern information, while group leaders organise and supervise members on the collective action activities expected to perform. These activities include farm information, maintenance of the tertiary canal, drain, farm road and structure after each irrigation season (Wongtragoon et al , 2009). Considering the vast area covered by irrigation, group leaders and local irrigation officers in MLIP are often unable to continuously monitor any possible irrigation rules violations (Kumnerdpet, 2010).…”

Performance diagnosis of Mae Lao irrigation scheme in Thailand (II). Application of the UIWDC model for water distribution system analysis

“…In the case of the MLIS, discharges are not measured even at major diversion points. As a tool to investigate such information, our group has developed the Unsteady Irrigation Water Distribution and Consumption (UIWDC) model, details of which are reported in the previous research (Wongtragoon et al 2009). The UIWDC model cannot reproduce an exact fact, but it is expected to show an essential relation of cause and effect.…”

“…The detailed description of the UIWDC model is referred in the previous article (Wongtragoon et al 2009). Only primary features are explained here.…”

“…Each Paddy Tank is composed of three tanks being set vertically. The upper, middle, and lower tanks represent ''ponding depth of the paddy field'', ''water content in the plow layer'', and ''ground water'', respectively (Wongtragoon et al 2009).…”