Development of process to enhance participatory community-based water management capacity for agriculture in Nan Province

Abstract

Water is an essential resource and input for agricultural, growing crop in particular. Agricultural transition, from subsistence to semi-commercialized cropping system with more intensive cropping pattern, driven by social-economic factors, pushed higher water demand. Small-scale water reservoir was developed to catch and meet the increased water demand. This well describes transitional context of Huay Muen reservoir and its supplied agricultural area. It holds 696,000 m3 capacity, supplies 1,490 rai of irrigated land. Farmers in this area could produce two crop seasons after harvesting rice. Farmers has formed water user group with well management. However due to limited water supply and intensive-complex-unseasonal cropping pattern, more diverse crops and planting dates, this made it difficult to manage water using traditional skill of "Kae-Muang " or community water manager. This also revealed possible risk to water scarcity under rainfall variability condition. This study aims at exploring livelihood and water management context and situation, create perception and awareness of farmers toward water management context and risk. Participatory approach and participatory geographic information system (PGIS) were employed to accomplish the objectives. The finding and employed approach, method and process were synthesized to formulate a practical guidance for community-based water management for agriculture that could be adapted and applied in other areas. Sustainable livelihood framework (LSF) and participatory method and tools were applied for livelihood context and situation analysis; accompanied by semi-structured and in-depth interview of sampled farmers and key informants. Field survey using acrial photo, land parcel map and farmers interview at farm place were conducted. The seasonal cropping calendar consists of wet-season rice and to crops after rice harvesting during dry season. Five major crops after rice are maize, peanut, sweet corn, pumpkin and leaf mustard. The irrigated area consists of 13 supplied zones, water was channeled through main canal and lateral canal that some of them are concrete and some are dirt canal. Using aerial photo draped with land use plot created from geographical information system, could help farmers to position their farm plot, neighboring farm plot and associated irrigation canal. This allowed them to see whole picture of the farmland and irrigation system. Focus group discussion resulted in understanding of livelihood context and livelihood dependency on agriculture especially cropping. It found that livelihood dependency for cash income and food on producing crops that mostly utilized water from the reservoir, non-agricultural activities such as labor waging and other jobs, and natural food gathered from forest area near the reservoir were 80%, 19% and 1% respectively. This confirmed the importance of the reservoir and also created awareness of the farmers with regard to water use and management. Field survey was conducted to quantify actual amount of water use for each crop that the farmers planted. The recorded data were cross section of the canal, water flow velocity and time of irrigated duration. Crop water requirement was also calculated using Penman-Monteith equation, local soil and weather data. These two water demand data were also compared with the crop water requirement data provided by the Royal Irrigation Department (RID). The crop water requirement determined by the RID for sweet corn, maize, pumpkin, and peanut were 324.8 m3, 540.81 m3, 504.69 m3 , 440.79 m3, and 303.62 m3 respectively. While, the amount of actual water use measured in the field and calculated from the Penman-Monteith method of both year 2018/ 2019 and year 2020/ 2021 were much higher than the RID references. The comparison of actual water use for growing crops after rice between year 2018/2019 and year 2020/2021 revealed drastic increase in water amount that the farmers supplied to all five crops, about two folds. The amount of water used in year 2018/ 19 for sweet corn, maize, pumpkin, peanut and leaf mustard were 1,152.3 m3 /rai, 510.53 m3/rai, 680 m3 /rai, 771.43 m3/rai and 417.83 m3 /rai respectively; while in the year 2020/2021 were 3,167.15 m3/rai, 1,892.59 m3/rai, 1,028 m3 /rai, 849.79 m3 /rai and 1,072 m3 /rai respectively.Amount of crop water requirement of year 2018/19 and year 2020/21 were also calculated using Cropwat 8.0 program to compare with the above data. It was found that the amount obtained from Cropwat 8.0 was lower than the actual measurement, and the calculated result of the year 2020/21 was higher than the year 2018/19. In year 2018/19, amount of crop water requirement per rai for sweet corn, maize, pumpkin, peanut and leaf mustard were 171.4 m3, 219.8 m3 , 268.7 m3, 291.6 m3 and 268.1. While in the year 2020/21 were 194.0 m3, 255.0 m3, 293.5 m3 , 304.5 m3 and 316 m3 respectively. This could be hypothesized that increase in water use was caused by difference of planting date and watering schedule of individual cultivated plot that required water supply asynchronously. Every occurrence of water supply, water had to rerun from the main canal to cach individual plot, instead of running from one to another continuously. In addition, the temperature in year 2020/21 was higher while rainfall was lower, this cause increasing in evaporation and evapotranspiration, thus required more water supply ompared to the year 2018/2019. The study results on livelihood context, current water management context and situation, and comparison of crop water requirement among the three methods above were present to the farmers as mean for dialogue and discussion. This feedback workshop stimulated discussion among the farmers. They could understand better the context and were aware of current situation and possible risk. The proposition of new regulation for better water management was agreed and emerged. The finding and experience gained from implementing this study were formulated as a guidance for practical community-based water management using participatory approach and PGIS with water user engagement that could be adapted and applied in other area.