This study aims at assessing the applicability of GIS and remote sensing as time-, cost- and labor-efficient tools in evaluating land characteristics and water balance inputs needed for efficient water management in irrigation schemes aimed at double rice cropping. The Ngamoeyeik Irrigation System in Lower Myanmar is our case study. Two scenes of LANDSAT 7 ETM+ data acquired at the beginning (January) and the end (April) of the irrigation season are used for land cover classification. Five categories of land use and land covers are identified for the January and the April classifications, showing high similarity with the ground data with an overall accuracy of 80 %. This is especially true for the rice paddy field category (96 %). From these land cover maps, the irrigated rice field category's distributions at the two different periods of the irrigation season were detected and rice field acreages accurately estimated. It is shown that using two land cover maps leads to more accurate and up-to-date information on land use and land cover conditions as well as on the rice field distributions and their temporal changes, and to more consistent rice field acreages than using a single land cover map. Irrigation water requirements and irrigation efficiencies are calculated and discussed in conjunction with water supply records in order to improve water management performances from the onfarm level to the overall irrigation system level.
Clustering of groundwater pump features in the groundwater development area is to enable a proper assessment of the potential environmental impact of pumping activities on groundwater sustainability. The present work concerns the application of fuzzy c-means approach to cluster the similarities of irrigation pumps features operating in the groundwater development area. The algorithm employs fuzzy partitioning system such that a given data point can belong to one or more cluster with the degree of belongingness specified by membership degree. The methodology is illustrated through the case study of groundwater pump system located in Madiun Regency, East Java-Indonesia. The results indicate that fuzzy c-means clustering applied in the operation characteristics of groundwater pumps seems to have reached encouraging results for the groundwater system under examination. The final result comprises of four groups; one group with low utilization and one group with high utilization of groundwater pumps for irrigation, whereas the remainder belonged to a less moderate utilization group and a moderate utilization group. Region I was dominated by shallow groundwater pumps with low discharge. Region II and III were dominated by medium to deep groundwater pumps. Another feature of the pumps operate in these regions was their usage below design potential. Meanwhile, pumps operating in Region IV was dominated by deep well pump and exploited more intensively than those in the other groups. The dependence on its groundwater sources and lack of a fixed irrigation system in Region IV were likely reason for its sharp increase in groundwater withdrawal, ignoring the adverse future impact on the environment. A further study is needed to map the spatial distribution of groundwater bodies considering the geology of the area, precipitation distribution, land use, and the density of pump wells. Results of the map of the groundwater potential zones can be used in combination with this finding result to decide the potential or possible locations of future groundwater development programs.
A mathematical model is proposed to describe spatio-temporal distribution of rainfall intensity. The model is a simple drift equation, which is a partial differential equation including drift terms. The coefficients of the drift equation are assumed to be constant in a storm event and are identified from observed rainfall data. The identification procedure uses a correlation analytic approach. In order to examine validity of the model, three observation networks have been set up since September 2005. Each observation network consists of three high resolution tipping-bucket raingauges with data loggers. The distance between two raingauge stations in an observation network varies from 824 m to 9,693 m. One of the observation networks is located in the temperate zone of Japan, while other two are in the coastal savanna zone and in the Guinea savanna zone of Ghana. The results of identification well represent local characteristics of rainfall distribution. Furthermore, it is suggested that reconstruction of spatio-temporally distributed rainfall data from the identified coefficients is prerequisite for advanced researches into runoff analysis, flood forecasting, and rainwater harvesting.
A fuzzy rule-based system, designed with genetic algorithm (GA), is developed for estimation of model parameter values of a distributed rainfall-runoff model, which consists of a number of physically influenced model parameters. Input cell-based physical characteristics of the watershed and output estimated model parameter values are expressed by different fuzzy classes, such as 'high', 'medium', 'low', etc. These classes are described by membership functions, and their effects on parameter values are defined by fuzzy rules. The cell-based model parameters are estimated from an optimized fuzzy system, where GA searches for optimal membership functions. To estimate the model parameters, the minimum summation of square errors is used as an objective function. The estimated river discharges using proposed model parameter estimation system at both calibration and verification periods show a good matching with observed discharges, with the model efficiency criterion R_2 of 96.67 and 94.57%, respectively. The index of volumetric fit V_f and the mean sum of square error E are obtained within well-acceptable ranges. The effects of various cell characteristics are also reflected very clearly in the estimated model parameters. The developed system has great potential to serve as a tool to estimate model parameters and to improve the model performance.
On small islands in Okinawa, surface drainage from farmlands is stored for agricultural usage in storage ponds constructed along the ends of watersheds due to the lack of large water resources. Water from farmlands contains much fertilizer and algae pollution. In such areas, although drop irrigation systems have been adopted, they are not useful because the pipes choked with algae. Algae growth depends on temperature, nutrition and light. Therefore, removal of such elements prevents water from being polluted by algae. The authors, therefore, tried to block the light by covering the water surface with sheets in order to prevents the algae growth in the ponds. The result was that this method was recognized as an efficient method of prevents the algae growth in the ponds.