Topographical and geological factors on gully-type debris flow in Malai River catchment, Siwaliks, Nepal

The Siwalik hill of Nepal lies in between the two major thrusts; Main boundary Thrust and Main Frontal Thrust. Thrusting and continuous erosion of material from surface causes several landslides and debris flow problem in the Siwalik region. Debris flow commonly occurs after landslide during heavy rainfall in the steep slope. This paper described about the topographical and geological controls on debris flow occurring in gullies in the Siwaliks of the Malai River catchment of mid-Western Nepal. The length of gully, length of debris channel, area of debris channel, area of catchment of debris flow, area of gully without debris flow were found using Google earth pro, a free version online database. Similarly, a form factor (F), average gradient of stream, slope area ratio and a topographical factor (T) were calculated. Lithology and geological structure were studied in the field. The relation between each factor was identified. Gully having larger debris flow event had T value greater than 0.01 and that having small debris flow event had T value less than 0.01. Gully without debris flow had T value less than 0.001. Gully having debris flow had F more than 0.1 and that free from debris flow had F less than 0.1. Both topographic and form factors were found greater than 0.1 at the hanging wall of the Malai Thrust, where large size debris flows were encountered. The T and F values obtained from the Middle and Upper Siwaliks were greater than 0.1.The number of debris flow events and large debris flows were found high the in the Middle and the Upper Siwaliks, and hanging wall of the Malai Thrust.

Dissociation of Measures of Topographical and Non-topographical Cognitive Ability in Older Adults

The relationship between topographical and non-topographical cognitive measures was studied for 25 elderly participants. The topographical measures were the Camden Topographical Recognition Memory Test (CTRMT), a Topographical Mental Rotation Test (TMRT), and a Virtual Pond Maze (VPM). The non-topographical tests were the Montreal Cognitive Assessment (MoCA), the Trail-Making Test-B (TMT-B), and a matching-to-sample Visual Short-Term Memory Test (VSMT). Only the correlation (0.48) between the TMT-B and the TMRT attained significance; the bivariate correlations among the three topographical measures were modest, ranging from 29 to 33, although they did correlate highly with a topographic composite score (0.69-0.78). A factor analysis yielded a further distinction between the topographical and non-topographical measures. Loadings for the three topographical measures on a presumed “topographical” factor ranged from 0.62 to 0.71 but only from 0.17 to 0.23 for the second factor. The MoCA and TMT-B loaded on both factors, while the VSMT measure loaded poorly (-0.03) on the topographical factor but highly (0.89) on the second factor. The results suggest that standard measures of cognitive function may not be optimal for specific assessment of topographical abilities, the best predictor of impending Alzheimer’s dementia.

EARLY TOWN PLANNING SYSTEM OF SMALL TOWNS IN PERAK

The township planning in Perak was affected post-signing of the Pangkor Treaty in 1874, as the state became the first state in Malaysian Peninsula intervened by the British. Introduction of grid system by the British has apparently affected the early layout of major cities such as Ipoh, Taiping, Kuala Lumpur, George Town and Singapore. This study attempts to investigate the theory of town planning during the British era after noticing a knowledge gap in regard to early town planning system of small towns in Perak. Based on purposive sampling using varying topographies as the criterion of site selection, 10 out of 20 small towns in Perak were selected for data collection. The small towns were Kuala Kurau, Klian Intan, Bagan Datoh, Lumut, Parit, Tanjung Rambutan, Pusing, Sungkai, Padang Rengas and Lenggong. Besides measured drawings, interviews were conducted with the locals and historical manuscripts of the research locale were also revisited. Based on comparative analysis, the study found that topographical factor was insignificant in influencing the early layout of small towns in Perak since linear system was used at different topographical background (riverside, coastal, hilly terrain and flatland areas). Moreover, location factor was found to be significant in terms of influencing the arrangement of early shophouse buildings into rows, which influenced the early layout of small towns in Perak.

Refinement of Topographical Factor For Estimating Soil Loss and Sediment Yield in Equatorial Regions

This paper aims to improve the Topographical Factor for estimation soil loss and sediment yield in Equatorial region. In the Revised Universal Soil Loss Equation (RUSLE), Topographical factor (LS) is derived as soil loss amount related to gently-inclined plane surface of 72.6ft (22.13m) slope length and 9% slope gradient in United States of America (USA). The terrains in equatorial region (especially at construction sites) comprise of more cone-shaped and pyramid- shaped characterized with steeper slopes and shorter slope lengths as compared to agricultural lands in USA. Topographical Factors (TT, TC & TP) in equatorial region were found as function of sediment yield (SY), surface runoff velocity (RV), and silt and clay compositions (SC). Triangular prism-shaped slope could be used as reference or indicator due to the shape is comparable or almost similar to that of the RUSLE’s gently-inclined plane surface. Cone-shaped and pyramid-shaped showed approximately 80% and 77%, respectively similar to triangular prism-shaped. Therefore, the Topographical Factors for triangular prism-shaped, cone-shaped and pyramid-shaped landscapes in equatorial region: Error! Reference source not found. (Triangular Prism), Error! Reference source not found. (Cone) andError! Reference source not found. (Pyramid).

Negative impacts of snow melting on the soil

Intensity of snowmelt erosion was computed for cadastral areas of Pohořelice, Strážnice, Kuchařovice, Holešov, Dukovany, Vizovice, Velké Meziříčí and Bystřice nad Pernštejnem on the base of 1980–2006 data for the period November to March. Mean long-term soil loss was estimated according to ZA­CHAR (1981) equation on the base of average rate of snowmelting, amount of melting water, outflow and infiltration characteristics, topographical factor, soil factor and vegetation factor. For the studied localities the average rate of snowmelting varied from 2.29 mm.day−1 to 7.90 mm.day−1. Also amount of melting water reached the maximum in Bystřice nad Pernštejnem in dependence on climatic region (6.11 cm of water column). Outflow and infiltration characteristics varied from 0.94 to 1.14. High va­lue of topographical factor (10.5) was assessed in Vizovice. Soil factor was estimated according to main soil unit from Estimated Pedologic-Ecological Unit EPEU. Its values varied from 0.31 in Velké Meziříčí to 0.47 in Holešov. Vegetation factor varied from 0.2938 in Vizovice to 0.4881 in Kuchařovice. Average soil loss as a consequence of snow melting varied in interval from 0.61 t.ha−1.year−1 in Pohořelice to 30.08 t. ha−1.year−1 in Vizovice.