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Wahyu Wisnu Wijaya, Wahyu Wisnu
Balai Penelitian Teknologi Kehutanan Pengelolaan Daerah Aliran Sungai

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Specific Peak Discharge of Two Catchments Covered by Teak Forest with Different Area Percentages Basuki, Tyas Mutiara; Adi, Rahardyan Nugroho; Wijaya, Wahyu Wisnu
Forum Geografi Vol 31, No 1 (2017): July 2017
Publisher : Universitas Muhammadiyah Surakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23917/forgeo.v31i1.3236

Abstract

In watershed area, forest has important roles in relation with peak discharge. This  research was conducted to study the impacts of teak forest on peak discharge. On-screen digitizing of IKONOS imagery was done to classify the land cover of the study area. Kejalen and Gagakan catchments covered by old teak forests by 74% and 53% respectively, were chosen as the study area. These catchments are located in Blora Regency. Automatic streamflow recorder was set at the outlet of each catchment and subsequently, peak discharges were examined from the recorded data. During the observation, there were 36 evidences of specific peak discharge. The results showed that a trend of lower peak discharges occurred in Kejalen catchment which has the higher percentage of teak forest area  in compared to Gagakan catchment with lower percentage of teak forest area, except when extreme rainfalls happened. At rainfall of 163 mm/day, specific peak discharge in Kejalen was higher than in Gagakan catchment. Although there is a relationship between specific peak discharge and the percentage of forest cover area, the increase of specific peak discharge is not only affected by forest cover, but also affected by daily rainfall, antecedent soil moisture, and rainfall intensity. Coefficients of determination between specific peak discharge and daily rainfall are 0.64 and 0.61 for Kejalen and Gagakan catchments, respectively.
Spatial Analysis of Land Degradation Susceptibility and Alternative Plants for Its Rehabilitation Auliyani, Diah; Basuki, Tyas Mutiara; Wijaya, Wahyu Wisnu
Forum Geografi Vol 33, No 1 (2019): July 2019
Publisher : Universitas Muhammadiyah Surakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23917/forgeo.v33i1.7499

Abstract

One of the drawbacks of developing plants for the rehabilitation of degraded land in Indonesia is the relative lack of information about species that are suited to the local conditions. Therefore, spatial information on land degradation and the plants suitable for rehabilitation is crucial. The objectives of this study were to map the susceptibility of land to degradation and to identify some alternative species for its rehabilitation. The research was conducted in Jang Watershed, Bintan Island, Kepulauan Riau Province, Indonesia. A quick assessment of land degradation was carried out to classify the degree of land susceptibility. The land suitability evaluation was conducted manually by matching the existing biophysical condition and plant growth requirements using a geographic information system. This analysis was applied for annual plants, such as Acacia mangium, Durio zibethinus, Artocarpus champeden, Theobroma cacao and Hevea brassiliensis. Furthermore, the maps of land susceptibility to degradation and species suitability were overlaid and the result was used to provide recommendations for rehabilitating the degraded land. This study showed that 22% of the Jang Watershed area can be categorised as highly susceptible to degradation. The suitability analysis illustrated that 59% of the degraded areas were suitable for Acacia mangium. The planting of fast-growing species such as Acacia mangium is expected to improve the physical, chemical and biological properties of the soil.