J. Appl. Environ. Biol. Sci., 2(6)232-243, 2012 © 2012, TextRoad Publication ISSN 2090-4274 Journal of Applied Environmental and Biological Sciences www.textroad.com *Corresponding Author: Evi Hendriarianti. Departement of Environmental Engineering , National Institute of Technology, Hydrogeometry And Water Quality Data Analysis For One Dimension Water Quality Modelling Of Lesti River At Malang Regency Evy Hendriarianti Departement of Environmental Engineering , National Institute of Technology, Malang ABSTRACT Decreasing of river water quality is one of the main environmental issues for Brantas River. Lesti River is one of the upstream section of Brantas River located on south east side of Malang Regency. Population growth with its attendant economic growth in this region affected environmental quality with the pollution from industrial, agricultural and domestic sources. Water resource managers must increasingly use analytical tools to assist in the formulation of sustainable water management strategies. To get an cohesively water quality management from upstream until dowstream, mathematical water quality modelling are needed. Water quality modelling need some data collection such as river hydrogeometry, river water quality and point source of polutant along the river. All colected datas were used to arrange objective model through analysing and scouping data process. Main objective of this research was carried out to know trend of historical of water quality besides hydrogeometry data. These primary and secondary data then analyze. A methode of collecting secondary data is surveyed by a related institution. A Tachimetry methode was used for determining a primary section of a river banks, buoyant plume methode for the river velocity measurement. Standar Methode of 1060 was used for water quality sampling. Those data, then analyze using discriptive statistical and linear regression. For the administration borders, Lesti river area covers Subdistricts of Sumbermanjing Wetan and Turen for the upstream, Subdist of Gedangan and Bantur for the middle and Subdistrict of Pagak for the downstream. Average flow for annual in ten years last range between 11,72 – 77,10 m 3 /sec with the average is 35,47 m 3 /sec. A decrease of a water quality occurs interms of physical parameters (TSS) and also that of other chemical parameters, such as DO, BOD, COD, Nitrate and Detergent. From this results, was decided to make those water quality models for Lesti River. Keywords : water quality, hydrogeometry, Lesti River, scouping for mathematical water quality modelling INTRODUCTION The problem of river water quality need an instrument to decide what action will takes. One of the instrument that can predict or simulate water quality changes are called water quality models. Because variability of physical and biochemical phenomena that can be affected water quality condition, it is important to define the objectives of the modeling process. This should involve discussions with stakeholders, regulating agencies, and technical personnel [1]. Brantas river is second biggest river area in Java Island. The area covers 15 (fifteen) regencies and municipalities in East Java Provinsi (Figure 1.) and Lesti river is upstream section of Brantas river. Figure 1. Map of Brantas River Area (Source : Bureau of Brantas Rivers District, 2002) LESTI RIVER