(Soekarno and Grace of 2006; Kline and Dolan, 2008; Zavodinsky and Gorkusha, 2014). River responses in maintaining the balance of water and sediment load ...
Mapping High Concervation Value Area for Ecosystem Services at Streams and Riparian Buffer By Idung Risdiyanto To determine the boundaries and map of riparian buffer using three approaches, that are (i) cross-sectional approach to river morphology and hydraulics of the water levels, (ii) riparian function approach and (iii) the dynamic approach of rivers meandering. Approach in points (i) and (ii) applied to all river course, while the approach (iii) only applied to meandering rivers.
1.
River morphology cross-section and hydraulics of water level approach
Determination of riparian buffer conducted by taking into account the characteristics of each rivers within the study area. This approach is conducted by recognizing the condition of the cross-section river morphology, ecology of plants found in the riverbanks, and the hydraulic condition of the water level associated with flood events (Maryono, 2009). With these three factors to determine the width of the riparian buffer can be divided into four parts consisting of: (i) floodplain, (ii) riverbank erosion, (iii) ecology banks, and (iv) security banks (Figure 1).
Figure 1.
Determination of Riparian buffer is based on cross-sectional morphology and water levels hydraulics (Source: Risdiyanto (2010) modified from Maryono (2009)
Mapping HCV4 area at Streams and Riparian Buffer by Idung Risdiyanto
1
2.
River function approach
As has been described in the previous section, riparian buffer has various functions, with each function having different benchmarks of the water body/stream. Protective and management measures of riparian areas need to be done to ensure the sustainability of the riparian functions. Functions of riparian zones that become determining factors for HCV area boundaries are as follows: Flood control (for rivers that have flood plains) - determined by TWI analyses; a similar approach to those used for swamps. Riverbank morpho-erosion control (for rivers with steep riverbanks) - determined by studying river cross section and hydraulic depth morphology. Water quality protection - determined by studying land cover and surface flow direction in the river catchment area. Riparian zones with good vegetation cover proven to protect water quality in the river are determined based on observations on the ground. Aquatic habitat protection – determined by considering the preferred habitats of protected aquatic wildlife with important conservation value. River shade trees that ensure a balanced microclimate with temperatures and humidity appropriate to the metabolisms of living creatures in the surrounding area – determined by considering the preferred habitats of protected aquatic wildlife with important conservation value. Terestrial wildlife habitats and corridors – determined by considering the preferences of high conservation value wildlife that use riparian zones as habitats, corridors, or sources of food. Indicative boundaries of these HCV areas are determined by following the most dominant of each functions. The minimum and maximum width of riparian buffer based on riparian buffer function approach is shown in Figure 2.
Mapping HCV4 area at Streams and Riparian Buffer by Idung Risdiyanto
2
Figure 2.
3.
The minimum and maximum limit of Riparian buffer width to ensure the sustainability of the river functions.(Adapted from: USDA Natural Resources Conservation Service. Where the Land and Water Meet: A Guide for Protection and Restoration of Riparian Areas First Edition. USDA NRCS, September 2003)
The river meanders dynamics system approach
According to Sukarno and Rohmat (2006), the occurrence of meanders caused by three major factors, namely: (i) the formation of meanders by hydraulic of the flow, (ii) the formation of meanders generated by the need for capacity and load-carrying ability from the upstream, and (iii) the formation of meanders caused by the least principle of work. When there is an imbalance of input and output of sediments through a particular piece of the river, channel by itself will make adjustments to maintain the balance. One meanders dimension on the channel will be formed at the time the channel is in equilibrium (Soekarno and Grace of 2006; Kline and Dolan, 2008; Zavodinsky and Gorkusha, 2014). River responses in maintaining the balance of water and sediment load caused the movement in the dynamics and changes of the flow patterns (Figure 3). The movement occurs alongside the river that make up a zone in the flood plain called the meander belt. Therefore, meander belt is an important space for the movement of river dynamics of Separi, Santan and Pampang river. Thus, defining the boundaries fo the riparian buffer on both sides should take into account the availability of space for meandering process, which occurs in the meander belt.
Mapping HCV4 area at Streams and Riparian Buffer by Idung Risdiyanto
3
Figure 3.
The movement of the river due to the meandering process as response of the river in balancing the load capacity of water and sediment from upstream (Source: Lane (1955) and Schumm (1984) in Kline and Dolan (2008))
Meanders corridor boundary different from riparian buffer in general. This area is not an area on either side of the river, but the function of the meander belt width and its buffer area (Figure 4). Meander belt width determined by the value of the widest amplitude meanders, thus provides room for the movement dynamics of river flow and sediment deposition. While the width of the buffer area is calculated from the outer boundary of the meanders belt. Space for erosion control is intended to prevent the input of the erosion results from land alongside the banks of the river or serve as sediment deposition area. While security banks are meant as a safety buffer area for meander belt and erosion control.
Figure 4.
Scheme method for determination of meandering river corridors in study area (Source: Credit Valley Conservation Authority: Regulation of Development, Interference with Wetlands and Alterations to Shorelines and watercourses And Out CVC WaterCourse and Valleyland Protection Policies, 2010)
Mapping HCV4 area at Streams and Riparian Buffer by Idung Risdiyanto
4
References :
Credit Valley Conservation Authority (CVC). 2010. Regulation of Development, Interference with Wetlands and Alterations to Shorelines and watercourses And Out CVC WaterCourse and Valleyland Protection Policies. Kline, M. & Dolan, K. 2008. River Corridor Protection Guide. Fluvial Geomorphic-Based Methodology to Reduce Flood hazards and Protect Water Quality. River Management Program. Vermont Agency of Natural Resources. Maryono, A. 2009. Kajian lebar sempadan sungai (studi kasus sungai-sungai di provinsi daerah istimewa yogyakarta) - A study of stream buffer width (case study of rivers in daerah istimewa yogyakarta province) (working paper) Risdiyanto, I. 2010. Bagaimana Mengukur Lebar Sempadan Sungai di Dalam Areal Perkebunan Sawit?. Bogor. (http://banyumilih.blogspot.com) Soekarno, I. & Rohmat, D. 2006. Proses Pembentukan Meander Sungai dan Hubungannya dengan Angkutan Sedimen (Percobaan Laboratorium). Jurnal JTM. U.S Department of Agriculture, Natural Resources Conservation Service. 2003. Where the Land and Water Meet: A Guide for Protection and Restoration of Riparian Areas. First Edition Zavodinsky, V.G. & Gorkusha, O.A. 2014. A Simple Physical Model of River Meandering. Journal of Geography, Environment and Earth Science International. 1(1): 1-8, 2014; Article no.JGEESI.2014.001. Sciencedomain International
Mapping HCV4 area at Streams and Riparian Buffer by Idung Risdiyanto
5
