Large fractal dimension of chaotic at tractor for earthquake sequence near Nurek reservoir

Fractal dimension of the chaotic attractor for earthquake sequence in Nurek dam based on 22.000 earthquakes detected during the period 1976-87 has been studied for this total period of observations as well as for the period from December 1977 to December 1987. The second period excluded increased seismic activity during second stage of filling the reservoir. Large fractal dimensions of the chaotic at tractor of 8.3 and 7.3 were found for the respective period which suggests the complexity of earthquake .dynamics in this region as compared to Koyna reservoir.

Mammal Persistence Along Riparian Forests in Western India Within a Hydropower Reservoir 55 Years Post Construction

While the negative impacts of dam construction on downstream river stretches and riparian forests are well studied, the status of wildlife presence and persistence in upstream reservoir deltas is virtually unknown. We investigated the drivers of terrestrial mammal occupancy and persistence along riparian forests of Koyna reservoir in western India 55 years after its construction. We adopted a catchment-wide field design grounded in the river continuum concept and sampled different stream orders within the reservoir. Camera traps, nested in an occupancy modeling framework, were deployed across 72 riparian sites and replicated for four seasons across all stream types. We recorded a total of nineteen species of terrestrial mammals during the study period. Multi-season occupancy models revealed three key patterns of mammal persistence: (a) ungulates were more frequently photo-captured in riparian forests; gaur and wild pig had the highest proportions of the total sampled area (0.84 ± 0.12 SE; 0.77 ± 0.07 SE, respectively); (b) small-sized ungulates were more vulnerable to local extinction than large-bodied ungulates; extinction probability was highest for barking deer (0.59 ± 0.07) and lowest for sambar (0.15 ± 0.07); and (c) distance from stream played major roles in determining mammal detection. Riparian forests are fundamentally important to ecosystem functioning and biodiversity conservation, and using the data from this study, managers can plan to sustain high mammal persistence along riparian forests at Koyna reservoir or similar Indian reserves. Further, our robust sampling approach, grounded in the terrestrial-riverine continuum concept, can be applied globally to understand species assemblages, aiding in multi-landscape and wildlife management planning.

Seismicity at Warna reservoir (near Koyna) through 1995

The Koyna Dam site in western India has been seismically active since its impounding in 1962. The seismicity peaked in 1967 when an earthquake of magnitude 6.3 claimed 200 human lives and caused some damage to the dam itself. Subsequently, bursts of seismicity with M ≧ 5 earthquakes have occurred during 1973, 1980, and 1993 to 1995. The epicenters during the latest burst are concentrated around the newly impounded Warna reservoir, 25 km south of Koyna. Several shocks of smaller magnitude have occurred in this area since 1967 under the influence of the Koyna (Shivajisagar) reservoir, but the impoundment of the Warna reservoir to over 60 m has led to the enhanced seismic activity in the region. The space-time pattern of epicenters located for the period 28 August 1993 to 31 December 1995 clearly delineates two parallel trends in the NNE-SSW direction. The correlation between seismic activity and water levels in both the reservoirs suggests that the present activity was influenced more by the Warna than the Koyna reservoir. The discriminatory characteristics of reservoir-induced seismicity based on b-value, foreshock-aftershock pattern, and decay rate of aftershocks continue to be valid.