Long-term changes in the within-season temporal profile of southwest monsoon over western India

This paper presents results of a study of long term trends in the characteristics of the within-season temporal profile of southwest monsoon rainfall over western India during the last five decades in relation to global warming induced regional climate change. In contrast to recent climate change analyses and projections, no significant long-term trends have been observed in this study. Slow decadal scale variations observed are analysed in relation to Pacific Decadal Oscillations (PDO). Daily variations in rainfall anomaly show opposite characteristics during negative and positive phases of PDO. The above-normal rainfall (>25%) is found during the starting phase of monsoon in negative PDO. Over the last decade, i.e., during 2000–2007, the seasonal rainfall amount, as well as seasonal span of southwest monsoon over western India is indicative of a gradual increase.     

Evaluation of spatial probability of landslides using bivariate and multivariate approaches in the Goriganga valley,Kumaun Himalaya,India

Natural Hazards - In this study, new hybrid artificial neural network (ANN) models were used for predicting the groundwater resource index. The salp swarm algorithm (SSA), particle swarm...     

An interpretation of wave refraction and its influence on foreshore sediment distribution

To analyze the grain size and depositional environment of the foreshore sediments, a study was undertaken on wave refraction along the wide sandy beaches of central Tamil Nadu coast. The nearshore waves approach the coast at 45° during the northeast(NE) monsoon, at 135° during the southwest(SW) monsoon and at 90° during the non-monsoon or fair-weather period with a predominant wave period of 8 and 10 s. A computer based wave refraction pattern is constructed to evaluate the trajectories of shoreward propagating waves along the coast in different seasons. The convergent wave rays during NE monsoon, leads to high energy wave condition which conveys a continuous erosion at foreshore region while divergent and inept condition of rays during the SW and non-monsoon, leads to moderate and less energy waves that clearly demarcates the rebuilt beach sediments through littoral sediment transport. The role of wave refraction in foreshore deposits was understood by grain size and depositional environment analysis. The presence of fine grains with the mixed population, during the NE monsoon reveals that the high energy wave condition and sediments were derived from beach and river environment. Conversely, the presence of medium grains with uniform population, during SW and non-monsoon attested less turbulence and sediments were derived from prolong propagation of onshore-offshore wave process.These upshots are apparently correlated with the in situ beach condition. On the whole, from this study it is understood that beaches underwent erosion during the NE monsoon and restored its original condition during the SW and non-monsoon seasons that exposed the stability of the beach and nearshore condition.     

Spatial Variability of Mass Movements in the Satluj Valley,Himachal Pradesh during 1990～2006

Satluj Valley is known to have a history of landslides and related mass movement activities since the geological times. Geological and geomorphological settings combined with anthropogenic activities constitute a propensity towards slope failure. During the last two decades,the area witnessed substantial increase in athropogenic pressure,mainly due to the exploitation of hydropower potential,changing landuse pattern and population growth. In addition,a shift of the climatic patterns in the form of larger area falling under the influence of rains was observed. These natural as well as anthropogenic changes in the area have resulted in increased spatial coverage of landslide in the area. This paper documents these changes during 1990～2006.     

Impacts of tourism development on the physical environment of Mussoorie,a hill station in the lower Himalayan range of India

Tourism in mountainous regions is a significant source of revenue generation. However, it has also been associated with many adverse environmental consequences. This study aims at assessing the negative impacts of the incessant upsurge in tourism development on the physical environment of Mussoorie, a well-known mountain tourist destination in India. The impact indicators for the region were identified and assessed by qualitative and quantitative analysis of field observations. The observations indicated the aggravation of traffic congestion, atmospheric pollution, undisposed solid waste, water scarcity and infrastructure unavailability as the prevalent issues, especially during the peak tourist months. The extent of the consequential damage to the environment was evaluated by conducting an assessment of tourism-induced human disturbance on the natural landscape of the town. Slope, slope aspect, vegetation cover, road network and drainage network were incorporated as the determining landscape attributes to prepare thematic maps of landscape quality (perceivable intrinsic properties) and landscape fragility (vulnerability to anthropogenic disturbances) using GIS technique. An absorption capacity map was finally prepared to characterize the study area into regions of different conservation needs. The results identified the need for planning appropriate preservation strategies for different tourist places in the town. The study can be used by the policy makers for implementing the regulatory measures against potential disturbances due to mass-tourism.     

Analysis of type of tectonic strain in polyphased deformed Molare area,Tessin, Switzerland,using deformed pebbles

The plots of axial ratios, X/Y and Y/Z, of deformed pebbles of quartz and quartzite occupy the constriction field. It is proved by comparision of observed data with the theoretical models, that the finite shapes of deformed pebbles showing constriction-type deformation ellipsoid has resulted due to superimposition of the schistosity forming flattening-type deformation of F₂ phase on the nappe forming flattening-type of F₁ deformation phase. The deformed shapes of pebbles indicate that the principal direction of maximum extension (X) of the finite deformation ellipsoid lie parallel to subparallel to the axial directions of F₂ and F₃ folds.

---

Zusammenfassung Diagrammdarstellungen der Achsenverhältnisse X/Y und Y/Z ergeben für deformierte Quarz- und Quarzitgerölle eine Lage im Konstriktionsfeld. Durch Vergleich der Beobachtungsdaten mit theoretischen Modellen wird nachgewiesen, daß die finiten Umrisse deformierter Gerölle mit einem Deformationsellipsoid vom Konstriktionstyp sich aus der überlagerung der die Schieferung verursachenden Deformationsphase F₂ mit Plättungstyp über die deckenbildende Deformationsphase F₁ mit Plättungstyp ergaben. Die deformierten Umrisse der Gerölle zeigen, daß die Hauptrichtung größter Extension (X) des finiten Deformationsellipsoides parallel oder annähernd parallel zur Achsenrichtung der F₂- und F₃-Falten liegt.

---

Résumé Les diagrammes de rapports d'axes X/Y et Y/Z relatifs à la déformation de galets de quartz et de quartzite montrent une localisation dans un champ de constriction. En comparant les données de l'observation avec des modèles théoriques on voit que les contours des galets déformés suivant un ellipsoÏde de déformation du type constriction résultent de la superposition de la phase de déformation F₂, du type applatissement, déterminant la schistosité, sur la phase de déformation F₁, du mÊme type, liée aux nappes. Les contours déformés des galets montrent que la direction principale de la plus grande extension (X) de l'ellipsoÏde de déformation affine est parallèle, ou approximativement parallèle, à la direction des axes des plis F₂ et F₃.

---

X/Y Y/Z . , F₂, , F₁ . , (X) , F₂ F₃.

     

Influence of magnetic fabric anisotropy on seismic wave velocity in paramagnetic granites from NW Himalaya: Results from preliminary investigations

Anisotropy of Magnetic Susceptibility (AMS) and seismic wave velocity studies of some paramagnetic Himalayan granitoids show good correlation between magnetic fabric anisotropy and P wave velocity (Vp). Vp shows strong positive correlation with magnetic lineation (L) and degree of magnetic anisotropy (P′) having correlation coefficient (r) values of 0.93 and 0.89 respectively. Both Vp and Vs show positive correlation with the SiO₂ content of Proterozoic and Paleozoic granitoids. Velocity of S wave (Vs) shows negative correlation with mean magnetic susceptibility (K_m) having ‘r’ value of 0.86. The correlation between Vs-K_m, V_p-P′, V_p-L also shows >95% probability in Spearman’s rank correlation. Based on the results from the present sample size it is suggested that, in paramagnetic granites, V_p is proportional to intensity of deformation and preferred orientation of minerals as well as the mineralogy. On the other hand, Vs is more dependent on the mineralogy alone.     

Influence of magnetic fabric anisotropy on seismic wave velocity in paramagnetic granites from NW Himalaya: Results from preliminary investigations

Anisotropy of Magnetic Susceptibility (AMS) and seismic wave velocity studies of some paramagnetic Himalayan granitoids show good correlation between magnetic fabric anisotropy and P wave velocity (Vp). Vp shows strong positive correlation with magnetic lineation (L) and degree of magnetic anisotropy (P′) having correlation coefficient (r) values of 0.93 and 0.89 respectively. Both Vp and Vs show positive correlation with the SiO₂ content of Proterozoic and Paleozoic granitoids. Velocity of S wave (Vs) shows negative correlation with mean magnetic susceptibility (K_m) having ‘r’ value of 0.86. The correlation between Vs-K_m, V_p-P′, V_p-L also shows >95% probability in Spearman’s rank correlation. Based on the results from the present sample size it is suggested that, in paramagnetic granites, V_p is proportional to intensity of deformation and preferred orientation of minerals as well as the mineralogy. On the other hand, Vs is more dependent on the mineralogy alone.     

Geomorphic portrait of the Little Rann of Kutch

Little Rann of Kutch is an integral part of the Rann of Kutch, occupying southeastern part of it. It remains a saline-inundated regime, partially seasonal and partially around the year. The study area experiences a very high ambient temperature at one point of time while it gets flooded by both the tidal water ingression and freshwater poured by the seasonal rivers during the monsoon season. And as a result, the area experiences a seasonal reversal of geomorphic processes which in turn is reflected through its distinctive and dynamic landforms. Geologically, this area was a part of oceanic floor and has immerged in the recent past. Geomorphology of the area plays a dominant role in the pattern and cause of saline water intrusion. The surface of Rann is at or slightly above sea level and possesses a monotonously plain character with some outcrop in the form of sandstone capped by basalts, resembling to island in the mid of the Rann. During 3 months of the southwest monsoon, storm tides, aided by the wind, force water from the Arabian Sea over the flat surface of the Ranns. Rainfall is fairly low, so that as the water recede and evaporate, they leave behind a crust of halite and gypsum crystals which grow in the clay and sands. This monotonously saline flat surface with annual inundation, have executed the Rann a mysterious piece of terrain. The characteristics and role of sediments in terms of erosional and depositional characteristics, their plasticity, facilitating capillary rise, their hygroscopic absorption capacity, infiltration capacity, permeability, etc. gives both short- and long-term implication to the area. Apart from the above concern, the soil has a great deal to play in terms of the vegetal and faunal cover. Considering these above characteristics, study area has been regionalized in order to have a better understanding and planning for the study area. The study area being an economic zone, also confronts with several environmental problems.     

Watershed Delineation in Flat Terrain of Thar Desert Region in North West India – A Semi Automated Approach Using DEM

Thar desert spreads in western part of Rajasthan, northern part of Gujarat, and some parts of Punjab and Haryana. The terrain is dominated by slightly sloping plains, broken by some dunes and low barren hills. The area is characterized by low average annual rainfall which is erratic in distribution and intensity. Drought will remain a major hindrance for agricultural production in Thar desert. Due to water stress condition, many watershed based development activities has been adopted by government and non-government organizations for the growth and sustainable development of this region. The need of this hour is preparation of a national level watershed atlas of 1:50,000 scale because majority of thematic maps are being produced presently on same or 1:10,000 scale. The manual delineation of watershed boundary in flat terrain based on topographic map will be time consuming and less accurate in the absence of prominent contour lines. Automated approach for watershed delineation using Digital Elevation Model (DEM) along a suitable algorithm has the advantage because the output is not only less time consuming but also independent from human decisions. Hence, a case study has been carried out in Churu sub-basin part of Indus basin which is located in Thar desert region. Depression less DEM with different spatial resolutions was used as input in hydrology tool of ArcGIS spatial analyst function for characterization of watersheds. The Churu sub-basin has been divided into various numbers of watersheds with an average size of 600 km². These watershed boundaries have been validated with respect to high resolution satellite imageries (IRS P6 LISS IV), Survey of India toposheets, ancillary data and limited field checks.