Automation of irrigation system design (water gate design and simulation of paddy field water level control system)

Abstract

Application of the System of Rice Intensification (SRI) needs to supply water intermittently in order to maintain water level around the soil surface. This needs more frequent operation of water gates and has become another heavy workload faced by farmers since most of the water gates made of metal materials and it is easily corosive. The objective of the study was to design water gates made of lighter materials with two function (regulator and measurement) which were also capable for applying automated irrigation. Mixtures of materials were conducted composed of concrete and glass fibre with varied treatments such as normal concrete (NC), fibre-concrete with 1 kg of fibre Woven Roving (FC1), FC2, FC3, fibre-concrete with 1 sheet Woven Roving (WR) in the midle of sample (FCM), and fibre-concrete with 1 sheet WR in the bottom (FCB). Furthermore, materials for fibreglass gate were used Chopped Strand Mat and WR with polyester resin (157 BQTN EX-Series). Material testings were conducted according to the Japanese Industrial Standard for Concrete (slump test, flexural strength, etc). The weight of a full fiberglass gate with its dimension of 150 cm x 54 cm x 1,2 cm was 15 kg. It has a flexural strength about 206 kg/cm2 for maximum deflection of 10 mm. While, the fibre-concrete has a maximum result of the FCB treatment with flexural strength 72 kg/cm2 and its dimension is 75 cm x 56 cm x 3 cm and 35 kg of weigth. The full fiberglass gate with round shape in the bottom has contraction coefcient (Cc) = 0,951, and a value of dischage coeficient (Cd) can be determined by 1 . . 1 0 1 k d c h k w h w C C         + - = ; with k0 = 15 and k1=0,062. Automation irrigation was conducted with a water balance model approach on SRI paddy field and fuzzy logic controller. The model inputs consist of climatic data and discharge capacity. The model is formulated to simulate various processes such as evapotranspiration, percolation, surface run off, depth of irrigation water and drainage to be applied on a daily. It is also simulates an automated daily ponding depth in the field used simple fuzzy logic control. The model could simulate the actual daily ponding depth of paddy with alternating shallow inundation (±2 cm) pretty well by treating a number and discharge capacity of actuator (solenoid valve) and set up a paddy levee height. Average performance index with Root Mean Square Error is about 8,41 in drought and rainy seasons, with value of f1 and f2 were 0,85 and 1,00.

Penerapan irigasi intermittent pada teknik budidaya padi SRI (System of Rice Intensification) membutuhkan pengaturan air yang akurat agar kadar air tanah tetap terjaga sesuai dengan kebutuhan tanaman. Pengaturan air irigasi di lahan persawahan umumnya menggunakan pintu air. Hal ini akan menjadi beban yang berat apabila dilakukan secara manual (konvensional) dalam penerapan SRI untuk skala luasan lahan yang lebih besar, misalnya 1 daerah irigasi (DI), mengingat pola kesetimbangan air yang sulit diperkirakan. Oleh sebab itu implementasi sistem kendali perlu dilakukan dalam pengaturan muka air di lahan padi sawah.