As a type of gate that is used to control the water level upstream, sluice gate is the gate with simple shape and outstanding ability to flush the sediment. The operation of the gate is considered an important process. The up and down movement of the gate would affect the velocity and cause local scour as the result of fluctuating rate. This research aims to assess the effects of discharge and gate-opening height variations, as well as the type of bedchannel material, on the change of depth of scour (d s ). The research was conducted of open channel flow model with a sluice gate able to up and down movement. The discharges used in the research were 9 types ranging from 1.0 to 5.0 dm . Calculated coefficient of determination of the relationship between two types of channel-bed material and the depth of scour was R 2 = 0.946. Consequently, it can be concluded that the equation can be applied on both types of bed-channel material.

Baseflow is essential for water resource management in the dry season at the watershed scale. Management strategy water resources play a crucial role, especially those related to estimation efforts water supply, water quality management, water balance calculation, and strategy development of other water resources. This study aims to determine the value of baseflow using the Fixed Interval Method. This study used Hydro Office software with input daily discharge data from 2004 to 2013. The average baseflow value obtained was 5.53 m3/s, the process of calibrating by taking discharge data in the dry season, with no rainfall input. The BFI value obtained an average of 0. 9. This value indicates that the Miu watershed has high storage permeability characteristics. It indicates that the Miu watershed has a relatively stable flow during dry periods. The greater the BFI value, the better the water supply in a watershed.

The operation of a damaged (jammed) sluice result unsuitable velocity distribution with the design. This causes turbulence of the flow which results the hydraulic jump. The hydraulic jumps as a function of energy absorbers. The large energy will cause damage to the water structure. Therefore, there is a need for research to obtain flow profiles. The aims of the research is to investigate the flow characteristic and hydraulics jump that occurred at downstream of manually moving of sluice gate. The height of opening gate set up variated at 0.4 cm to 1.4 cm. The range of using variated discharge from 0.108 lt/s to 0.524 lt/s. The result of investigation showed that the higher of opening gate at the same discharge value the hydraulics characteristic at the downstream of sluice gate decreasing. The hydraulics characteristic are the water depth, hydraulics jump and the flow characteristic. As a results variation discharge and opening gate are subcritical flow.

The aim is to know the effect of bedload sediment to river hydraulics parameters. The research was conducted by taking samples in three-part of the river. Each location is taken ten cross-sections with left, middle, and right parts of the river. Bedload sediment is calculated by the grain analysis method. There are several approaches in determining the roughness: Manning, Raudkivi, Subramanya, Meyer, and Muller roughness. From the analysis results, sediment in the form of fine sediment (d ≤ 0.15 mm) located in the middle of the cross-section does not settle due to high velocity. In contrast, in the wet area, the velocity is smaller so that grain material is deposited. The relationship of bedload sediment to the morphological form of the river shows that the middle part has the most material content in grain sediment (d ≤ 0.15 mm). The wet edge has the most content in gravel and sand (d < 6 mm). The Manning equation obtained a minimum roughness of 0.0257 and a maximum coefficient of 0.0365 with an average value of 0.0311. This value is matched with the coefficient of roughness on the Manning table does not differ much, i.e., natural, straight, and meandering channels.

Climate change in Indonesia is marked by changes in temperature, rainfall patterns, sea level and climate variability. The climate condition of the Sausu watershed is a natural process that occurs in a rainfall patterns, magnitude and changes in air temperature. This study was conducted to identify the dangers of climate change to the water sector in the Sausu watershed. The analytical method used is Modified Penman evapotranspiration, water balance analysis model F.J. Mock, Makesens, Cumulative Distribution Frequency (CDF) statistical analysis and hazard weighting. This study uses secondary data, namely rainfall sourced from the Sausu rain station in 2002-2021 and climate data (climatology) sourced from BMKG in 2002-2021. Results from this study is that climate change occurs in the Sausu watershed which is characterized by a positive Z value (an increasing trend) and negative (a decreasing trend). A positive Z value (increasing trend) occurs in June, and a negative Z value (declining trend) occurs in December. The danger of decreasing water availability (PKA) occurs in the period 2052-2061 with a low level of danger. Flood hazard occurs in the period 2052-2061 with a high level of danger. Drought hazards occur in the period 2042-2051 and the period 2052-2061 with a low level of danger.