Exceptional heavy rainfall over Ajoy, Mayurakshi and Kansabati catchments and QPF verification during flood season of September 2009

Ajoy, Mayurakshi, Kansabati are three important river catchments of West Bengal and Jharkhand state, received very heavy rainfall during two consecutive days of flood season in the month of September 2009. The contribution of heavy rainfall & combined discharges from Damodar Valley Corporation (DVC) reservoirs during the period of heavy rainspells over these catchments enhanced flood situation in some districts of West Bengal. The synoptic features based on weather charts, cloud imageries of satellite and radar pictures have been taken to analyse. The realized areal average precipitation (AAP) as per rainfall recorded at 0300 UTC of next day have also been taken to verify the quantitative precipitation forecast (QPF) of 6&7 September 2009.

Diet and isotopic niche dimensions of predatory fish in two estuaries with different degrees of anthropogenic disturbances: a case study of Wami and Pangani Tanzanian coastal estuaries

Diverse anthropogenic activities including alteration of hydrological regime and agricultural development in the upstream of the river catchments modify the structural components and ecological roles of the species in estuarine ecosystems. The present study compared the diet, carbon (δ13C) and nitrogen (δ15N) isotopic signals, trophic niches and metrics of trophic redundancy of predatory fish and their potential phytodetritivore prey-fish between two estuaries with different degrees of anthropogenic disturbances. The δ13C and δ15N signals, Bayesian mixing models and stomach content analyses were adopted. It was revealed that the diet among the predators Arius africanus, Epinephelus coioides, Sillago sihama and Pomadasys argenteus and their isotopic signals including their phytodetritivore-prey, Valamugil buchanani were significantly different between Wami and Pangani estuaries (PERMANOVA, Pseudo –F ≥ 3.1, p = 0.05). The total isotopic niche area between estuaries accounted by the comparable Bayesian standard ellipse area (SEAb) was significantly smaller in Wami than that of Pangani (t-test, t = 4.3, p < .001). The ANOVA test further confirmed significant variation in SEAb among fish populations in two estuaries (F = 27.84, p < 0.001). The Layman metric indices of trophic diversity and redundancy of Wami estuary were substantially smaller than those observed at Pangani estuary. These findings mean that despite Wami estuary being under conservation status, the extent of disturbances in the upstream is high enough to induce the ecological changes at the base of the food web, subsequently cascading its effect up to the higher-order consumers of the ecosystem. As a result, the ecological redundancy and ecosystem complexity of Wami is somewhat compromised relative to that of Pangani estuary. Therefore, the degree of anthropogenic disturbances in river catchments affect differently the trophic niches of predatory and phytodetritivore fish and hence overall food web structures, trophic redundancy and complexity of estuarine ecosystems.

A Synoptic analogue model to issue QPF over Gangetic West Bengal and adjoining Jharkhand

In this study the Areal Average Precipitation (AAP) data for each day over each of the six catchments of Gangetic West Bengal (GWB) and adjoining Jharkhand namely river catchments of Mayurakhshi, Ajoy, Kansabati, Damodar, Barakar and Lower Valley of Damodar Valley Corporation during monsoon season for 25 years from 1990 to 2014 have been analyzed by grouping the AAP in three different ranges (11-25 mm, 26-50 mm, 51-100 mm and more), excluding Mainly Dry and 01-10 mm. The associated main synoptic features viz., trough at mean sea level, low pressure area, well marked low pressure area, cyclonic storm and cyclonic circulation for each day and their location with respect to the river catchments, viz., over the catchment, neighbourhood of the catchment (within 200 km South or North) and outside the catchment (more than 200 km South or North) have also been studied. The association of AAP ranges over six catchments with different categories of synoptic features has been examined. The distribution of percentage frequency of AAPs associated with the category of synoptic feature for the period 1990 to 2014 has led to development of a Synoptic Analogue Model (SAM) for issue of Quantitative Precipitation Forecast (QPF). The results obtained from SAM have been verified for rainfall data and calculated AAPs of monsoon season of 2015 over all the catchments and different skills scores also presented in this study.

Basin Analysis of Tertiary Strata in Golden Bay, Nelson

<p>Eocene to Miocene strata comprise the Brunner Coal Measures (Ak-Ld), Takaka Limestone (Ld-Po), Tarakohe Mudstone (P1-S1) and Waitui Sandstone (Sc-Sl), and form a transgressive-regressive sequence on an essentially stable structural platform. Brunner Coal Measures in the Takaka valley (up to 350m thick) consist of cross-bedded sand and gravel, interlaminated sand and silt, bioturbated muddy sandstone, carbonaceous mudstone and coal. Five facies associations are recognized and interpreted as river/floodbasin, estuarine and shallow marine deposits. In the Aorere and Parapara River catchments, two new members are recognized: the Quartz Wash Member, comprising quartzose sand and conglomerate, and the Washbourn Limonite Member, a sedimentary iron-ore deposit. The Takaka Limestone (up to 100m thick), consists of bryozoan, bivalve or sandy grainstone or packstone, deposited on a tidal current-swept shallow-middle shelf with minimal terrigenous influx. Diagenesis was controlled by pressure-solution during deep burial, and resulted in a rightly cemented rock with dolomite and neomorphic features. The Tarakohe Mudstone (up to 900m thick) is dominated in its lower half by massive mudstone of hemipelagic and turbiditic origin, and in its upper half by shallow shelf-estuarine sandstones and mudstones. The Waitui Sandstone (160m thick) comprises shallow marine sandstone. Deposition of the Brunner Coal Measures took place in localized fault-angle depressions. The Takaka Limestone was deposited during a period of regional subsidence and minimal tectonic activity. The Tarakohe Mudstone and Waitui Sandstone were deposited in synclinal basins which were later modified by rising monoclinal boundaries.</p>

Basin Analysis of Tertiary Strata in Golden Bay, Nelson

<p>Eocene to Miocene strata comprise the Brunner Coal Measures (Ak-Ld), Takaka Limestone (Ld-Po), Tarakohe Mudstone (P1-S1) and Waitui Sandstone (Sc-Sl), and form a transgressive-regressive sequence on an essentially stable structural platform. Brunner Coal Measures in the Takaka valley (up to 350m thick) consist of cross-bedded sand and gravel, interlaminated sand and silt, bioturbated muddy sandstone, carbonaceous mudstone and coal. Five facies associations are recognized and interpreted as river/floodbasin, estuarine and shallow marine deposits. In the Aorere and Parapara River catchments, two new members are recognized: the Quartz Wash Member, comprising quartzose sand and conglomerate, and the Washbourn Limonite Member, a sedimentary iron-ore deposit. The Takaka Limestone (up to 100m thick), consists of bryozoan, bivalve or sandy grainstone or packstone, deposited on a tidal current-swept shallow-middle shelf with minimal terrigenous influx. Diagenesis was controlled by pressure-solution during deep burial, and resulted in a rightly cemented rock with dolomite and neomorphic features. The Tarakohe Mudstone (up to 900m thick) is dominated in its lower half by massive mudstone of hemipelagic and turbiditic origin, and in its upper half by shallow shelf-estuarine sandstones and mudstones. The Waitui Sandstone (160m thick) comprises shallow marine sandstone. Deposition of the Brunner Coal Measures took place in localized fault-angle depressions. The Takaka Limestone was deposited during a period of regional subsidence and minimal tectonic activity. The Tarakohe Mudstone and Waitui Sandstone were deposited in synclinal basins which were later modified by rising monoclinal boundaries.</p>

Major-Ion Chemistry and Quality of Water in Rivers of Northern West Siberia

This study reports a synthesis of years-long hydrogeochemical monitoring in northern West Siberia, performed by the Russian Meteorological Service (Rosgidromet) and several academic institutions. Natural factors and intensive human economic activity lead to the disruption of the ecosystems of the northern territories of Western Siberia. The aim of this study is to estimate the background water chemistry parameters in the rivers of northern West Siberia in the beginning of the 21st century. The mean values hydrochemical and geochemical indicators were determined with STATISTICA software, which can be used as background values in assessing the actual and allowable anthropogenic impact on water bodies. We revealed four water chemistry provinces: western Ob Gulf and Ob estuary catchments (I); eastern Ob Gulf and Taz Gulf catchments, except for the Taz River and its tributaries (II); Taz River catchments (III); Yenisei River catchments, right bank (IV). The major-ion chemistry of the sampled river waters records a combination of geological, geomorphological, and hydrological conditions in the four provinces. The features typical of the northern West Siberian Plain are especially prominent in province II, which has the lowest average total of major ions (Σmi), the highest chemical oxygen demand (potassium dichromate COD), and the highest contents of Fe and phosphates. The Σmi value is the highest in province IV. The river waters from four provinces share similarity in quite high organic contents (both potassium dichromate and permanganate COD), as well as high NH4+ and Fe. The long-term average Σmi of the waters is predicted not to change much in the coming one or two decades, though it may decrease slightly in the winter season but increase in the fall and spring time.

Determination of Cover Management and Soil Loss Risk Mapping by Sub-Districts and River Catchments of Cameron Highlands Malaysia

Uncontrolled deforestation and land clearing for agricultural, urban development, and infrastructure construction without considering cover management (C&P) factors have resulted in severe soil erosion over the land surface of Cameron Highlands in the state of Pahang, Malaysia. Thus, this study determines the C&P factors for the Universal Soil Loss Equation (USLE) to forecast soil loss risk. Land use and land cover recorded by PLANMalaysia and the Department of Agriculture (DOA) Malaysia have produced different C&P factors in Cameron Highlands. The C&P factor produced from PLANMalaysia and the DOA has values ranging between 0.01 to 1.00 and 0.30 to 0.49, respectively. Since the C&P factor varies according to the data source, this study combined both data sources to capture both agricultural and urban development impacts, resulting in an acceptable C&P factor. These new C&P factors have improved the prediction of soil loss risk with 15.63% (10,581.86 hectares) of the Cameron Highlands area classified as having a moderate–critical soil loss risk compared to DOA 7.16% (4844.97 hectares) and PLANMalaysia’s 11.46% (7725.26 hectares). Thus, local authorities must strengthen all regulations and policies to address the predicted moderate–critical soil loss risk in Cameron Highlands, thereby preventing severe soil erosion.

Deformation between the highly oblique Yakutat–North American plate boundary and the Eastern Denali fault

This study investigates the spatial and temporal pattern of rock exhumation inboard of the highly oblique Yakutat–North American plate boundary. We aim to quantify how far deformation is transferred inboard of the Fairweather transform plate boundary and across the Eastern Denali fault. We present new detrital apatite and zircon fission track data from 27 modern drainages collected on both sides of the Eastern Denali fault and from the Alsek and Tatshenshini River catchments that drain the mountainous region between the Fairweather fault and the Eastern Denali fault. By integrating our data with published bedrock and detrital geochronology and thermochronology, we show that exhumation reaches much farther inboard (&gt;100 km) of the Fairweather fault than farther north in the St. Elias syntaxial region (&lt;30 km). This suggests that the entire corridor between the Fairweather and Eastern Denali faults exhumed since mid-Miocene time. The Eastern Denali fault appears to be the backstop, and late Cenozoic exhumation northeast of the fault is very limited.