Prediction of Spatial Distribution of Organic Carbon in Lower Brahmaputra Active Floodplain Soils of Bangladesh

Soil acts as a large reservoir of Organic Carbon (OC) but the amount varies significantly with space and time. Thus, soil analysis and interpretation of spatial variability of Soil Organic Carbon (SOC) are keys to site-specific management. The study aimed to characterize the spatial variability of SOC in an active floodplain. Soil samples were collected in three major landform categories (natural levee, back slope, marsh land) from the lower Brahmaputra River floodplain and then analyzed for SOC measurement in the laboratory. The measured data were then analyzed for spatial variability interpretation using descriptive statistics and geo-statistical analysis. The study found that the amount of SOC varies with landform variation, soil texture and distance between sample points. The topsoil of marsh land has the highest (1.41%), back slope holds a moderate amount (1.15%) and the natural levee has the lowest (0.75%) amount of SOC. The amount of clay particles at the top layer was found to be positively correlated to the SOC whereas in the same layer of sand and silt showed a negative correlation. The geo-statistical analysis illustrated the nugget effect. Low (<1%) SOC is commonly found in the agricultural soils of Bangladesh which was corroborated in this study; moderate (1.1%) SOC was found in the floodplain. This study aimed to provide an insight into spatial variability to assist in predicting SOC in the active floodplain; consequently, the interpretation of spatial variability analysis can be implemented for site specific management strategies and to calculate carbon stock in floodplain soils. The Dhaka University Journal of Earth and Environmental Sciences, Vol. 8(2), 2019, P 33-40

A flume study to investigate the contribution of main-channel bedforms on levee formation

Natural levees can be observed worldwide in nearly all river systems characterized by frequent flooding in combination with the transport of suspended bed material. Several parameters and processes have been suggested to explain the formation and the highly variable geometry of natural levees. However, the effect of bedforms migrating in the main-channel has not been amongst the studied parameters and processes. To fill this gap, this study investigates the relationship between bedforms and natural levee formation by flume experiments. Experiments were conducted in a 2 m wide and 30 m long sediment recirculating flume, monitoring the bed level elevation in the main channel by ultrasonic sensors as well as recording the levee development on the floodplain by a camera. The effect of different bed configurations on the developed levees is compared, and discussed, showing that bedforms could enhance levee formation.

KARAKTERISTIK FISIK LAHAN DI NAGARI PARU (RIMBO LARANGAN) KABUPATEN SIJUNJUNG

Indonesia is a country that has a tropical climate, tropical climate caused so much rain during the year compared to the dry season. With the tropical climate of Indonesia has a region dominated by forests that are the lungs of the world. One of the existing forests are forests located in the District Lung Nagari Sijunjung Sijunjung or better known by local people with the name Rimbo Prohibition. This study aims to find out about the physical karaksteristik land (slope, landform, hydrology) in Rimbo Prohibition in Nagari Lung District of Sijunjung Sijunjung, knowing how the utilization of land by the community around Rimbo Prohibition. This type of research is descriptive. The results showed that the physical characteristics of the land is very varied Prohibition Rimbo, Rimbo height of Prohibition highly variable, then the slope in Rimbo Laranagn also vary. Landform in Rimbo ban can be divided into three parts, namely the karst hills, alluvial plains and natural levee. Hydrological conditions in the sub-basins of lung depends on the streams flowing from Rimbo Prohibition. Land use specially designated as forests. With Prohibition Rimbo characteristics that vary widely made public memamfaatkan forest products as needed to make Rimbo Prohibition awake d beauty.Keywords: physical characteristics of the land, the use of Rimbo Prohibition

Geo-tourism Potential of Sand Bars and Oxbow lake at Buluh Cina, Kampar – Riau, Indonesia

Buluh Cina Village is located at Siak Hulu District, Kampar Regency, Riau Province and its about 25 km from Pekanbaru City. This Village is designated as Tourism Village by The Government of Riau Province. This research aims to optimize the potential Geo-tourism by understanding the strengths and weaknesses aspect which is owned by Buluh China Village. So it can increase the number of tourists who visit Buluh Cina Village. The method used is the field survey and literature review. The village is surrounded by a tropical rain forest with an area of over 100 hectares and it divided by the Kampar Kanan River. Fluvial Meandering System of this river form the main channel (river), sandbars, natural levee, floodplain and oxbow lake. Geo-tourism potential that can be developed are sand bars and oxbow lake. Buluh China Village has had a tourist attraction, but there are still some weaknesses, such as floods in the rainy season and some support facilities are not optimal.

The 2015 Flood Impact due to the Overflow and Dike Breach of Kinu River in Joso City, Japan

Heavy rainfall in September 2015 inundated the Kinu River basin and caused an overflow and dike breach of the river in the eastern part of Joso City, Ibaraki Prefecture, Japan. The area, which is bounded by the Kinu and Kokai Rivers, experienced deep inundation of more than 2.5 m, which continued for more than 3 days at the maximum level. Although the estimated maximum inundation depth and duration were basically related to the elevation and distribution of topographic surfaces, strong flood flow washed buildings away near the overflow and dike breach sites and caused deep inundation even though these sites were located on a relatively higher natural levee. In addition, serious damages such as interruption of emergency transportation routes and deep inundation over floor level occurred, isolating evacuation centers and important facilities including a municipal hall and hospitals. Few residents utilized the pre-prepared flood hazard map or understood the local geography, and evacuation orders were not fully transmitted to the local residents, which might have increased the flood’s impact.