Environmental Flow Assessment Using Water-Sediment Approach at the Sekampung River, Indonesia

Abstract

Environmental issue has been considered more significant in many aspects of engineering decision-making process particularly in river management. There is an increasing effort to conserve functioning of rivers for human use as well as nature, therefore environmental flow assessment has been widely developed. This paper discusses on environmental flow assessment of the Sekampung River, particularly on its middle reach. A new analytical approach based on water-sediment equations was introduced in order to determine a minimum environmental flow at the certain cross section of a river. The result of the new method was then compared with a minimum environmental flow provided by using two hydrological based methods, namely, Tennant and Flow Duration Curve Analysis (FDCA) method. The result shows that the concerned discharge provided by the water-sediment method (3.5 m 3 /s) is the smallest compare with a minimum environmental flow that is provided by both Tennant (5.7 m 3 /s) and FDCA method (4.5 m 3 /s). It is promising that the water-sediment method can be used as a simple approach on preliminary state of environmental flow assessment. The method involves not only water discharge but also its related sediment flow of the river in order to mitigate further ecological and morphological risks.

Lake water based isoscape in central-south Chile reflects meteoric water

“…Lake watershed delimiting and classification reveals that all lakes in this study are hydrologically open. A slope index percentage was generated to assess the average steepness of each drainage area, following a previously determined guideline 22 , where percentages indicate terrain as follows: 0–3% is flat, 3–8% is undulating, 8–15% is moderately sloping, 15–30% is hilly, 30–45% is moderately steep, 45–65% is steep, and > 65% is very steep. The average slope of the lakes is 26%, or hilly.…”

“…The watershed was then delimited, with corrections made to better define the edges of each polygon used to calculate boundaries, such as erasing small polygons that were interpreted as noise. Slope was also calculated according to methods/ranges proposed by the United States Department of Agriculture 22 so that each watershed is described with a slope characteristic, with slope gradient classes above 45 indicating steep drainage basins. The land uses were calculated from Chilean vegetative data 20 .…”

The challenges in implementing the environmental flow concept in Indonesia

“…There are two scientific articles in 2014 and 2015 that related to environmental flow. The first one is in the assesment of environmental flow based on water-sediment relationship in Sekampung River, Lampung Province, Sumatra [28]. It is a part of the doctoral thesis [29] that the same author finished just a year after the publication of the paper.…”

Environmental flow assessment of Kayan River: managing sustainability indicator of hydropower project

“…However, a minimum environmental flow is a significant threshold to maintain the river environment [1,2]. The flow is a minimum water flow that must be preserved to maintain environmental value and the environmental capacity to support ecological systems along the river [3,4]. On the other hand, uncertainty is the main issue on how and what an environmental flow should be provided [5].…”

“…Reviews [1,4,[7][8][9] identify four types of environmental flow methods commonly used to identify the minimum environmental flow: hydrological, hydraulic rating, habitat simulation, and holistic methods.…”