Alluvial Areas Research Articles

The stabilization of soft soil using admixture of palm oil boiler ash and MATOS

Banjarmasin has an alluvial area with soft soil thickness of 28-42.4m. Therefore, the land is not structurally feasible for construction due to the low California Bearing Ratio (CBR). One of the solutions used to overcome this problem is soil stabilization. This study aims to examine the effect of adding palm oil boiler ash and MATOS in accordance with CBR value to stabilize soil conditions. The laboratory CBR method was used to determine the original and stabilized conditions of the soil. The initial and stabilized soils used an admixture of 2% MATOS as an additive and palm oil boiler ash with percentage variations of 6%, 9%, and 12% of the dry weight soil. This was further kept for 7 days curing before being tested. The result showed that the highest CBR value is obtained at the variation of 6% palm oil boiler ash + 2% MATOS with an increase in CBR value of 7.542% from the original soil condition.

Downstream Decreasing Channel Capacity of a Monsoon-dominated Bengal Basin River: A Case Study of Dwarkeswar River, Eastern India

Downstream changes in channel morphology and flow over the ephemeral Dwarkeswar River in the western part of the Bengal Basin, eastren India were investigated. The river stretches from the Proterozoic Granite Gneiss Complex to the recent Holocene alluvium, forming three distinctive geomorphological regions across the river basin: the pediplane and upper and lower alluvial areas. Sixty cross-sections from throughout the main trunk stream were surveyed and the bankfull width, depth, cross-sectional area, and maximum depth were measured. Sediment samples from each location were studied and the flow velocity, stream power, Manning’s roughness coefficient, and shear stress were estimated. The results show that the bankfull channel cross-section area, width, width-to-depth ratio, and channel capacity increased between the beginning and middle of the river. Thereafter, the size of the river started to decrease in the lower alluvial area. This was characterized by gentle gradients, cohesive bank materials with grass cover, and channel switching. Within the lower part of the river, the channel capacity was observed to diminish as the drainage area increased. This increased the bankfull flow frequency and accelerated large floodwater losses in the floodplain via overbank flows and floodways.

Is the topography playing a dual role in controlling downstream channel morphology of a monsoon dominated Dwarkeswar River, Eastern India?

This study focuses on the role of topography in downstream changes in channel morphology of a monsoon dominated Dwarkeswar River with sixty cross-sections. Bankfull channel characteristics, flow characteristics, sediment characteristics and channel pattern were analysed with respect to dissected plateau, plateau-fringe and alluvial plain using statistical analysis. There was a significantly positive relation with distance from source and width (r = 0.874), width/depth ratio (r = 0.607) and flow area (r = 0.926) in the dissected plateau, although a significantly negative relation was found in the alluvial plain (width (r = −0.963), width/depth ratio (r = −0.897), and flow area (r = −0.821)). Overall, the channel dimensions diminished in the alluvial area by 6–7 times. In both these cases, TSI values were higher than the HSI. In the PCA-1, topographic factors were more dominant and the role of drainage area, elevation, slope, basin shape and depth of sediment were opposite to each other in comparison with dissected plateau and alluvial plain.

Study on Performance of Cement Mixing Pile in Marine and Continental Deposition Soft Soil Area

Soft soil was widely distributed in the coastal area, and the key characters were high water content and low capacity. Cement Mixing Pile (CMP) is an effective method to treat soft soil foundation. While CMP construction quality was difficult to control and it was of different reinforce effect for different geology origin. In this paper, five geology origins have been divided for the littoral area, lagoon area, alluvial area (Yangtse River), alluvial area (Ancient Yellow River) and lacustrine area. CMP, used in 26 expressways which were constructed during the period of 2008 - 2016, has been divided two-part (Upper & Lower part) to test the construction quality of CMP through Standard Penetration Test (SPT), Unconfined Compaction Strength (UCS) and Cement Mixing Pile Quality Designation (CMPQD). Results show that geology origins have great influence on the construction quality of CMP at the same construction maintenance condition. Depth has a significant effect on UCS of the lower part of CMP while the little effect on UCS of the upper part. Construction quality of long CMP was more difficult to control than short CMP. The high quality of the upper part may cause the unqualified lower part evaluated as qualified or good, which may lead to some engineering accidents.

Archaeo-geophysical survey of Bronze and Iron Age fortress landscapes of the South Caucasus

Bronze and Iron Age fortresses in South Caucasia have long been interpreted as evidence for the region's first territorial polities with complex bureaucracies, but it has only been through recent intensive survey and examination of settlements beside fortresses that archaeologists have developed a better understanding of the inhabitants of fortress-polities and their landscapes. Near-surface geophysical prospection near two hillforts overlooking the Arpaçay river valley, Naxçıvan Autonomous Republic, Azerbaijan, evaluated previously published hypotheses about Bronze and Iron Age fortresses. These two forts, Oğlanqala, a 12-hectare hilltop fortress inhabited in the Iron Age, and Qızqala 1, a 2-hectare fort with Middle Bronze Age and Iron Age pottery, were previously documented through survey and excavations as part of the Naxçıvan Archaeological Project (NAP). Ground-penetrating radar (GPR) and magnetic gradiometry surveys focused on areas of potential significance identified in the NAP. Magnetic gradiometry survey in the plain between Oğlanqala and Qızqala located a fortification wall segment that connects to previously recorded surface features argued to date to the Middle Iron Age; the path of this wall lends support to the hypothesis that it enclosed least 324 ha surrounding Oğlanqala and Qızqala and limited access to a narrow mountain pass and fertile lands in the river valley. Geophysical prospection at a settlement site on a bedrock shelf near Qızqala 1 suggests that architectural remains are preserved within part of the large enclosure. Geophysical prospection elsewhere in the alluvial plain did not reveal evidence for preserved architecture within or outside of the hypothesized enclosure, though this could be a result of soil conditions. Magnetic gradiometry of a Middle Bronze Age kurgan field outside of the enclosure identified the potential locations of burials that were not identified during surface survey. New sources of historical satellite imagery aided interpretation of geophysics results from highly-disturbed alluvial areas.

Flash floods and groundwater evaluation for the non-gauged dryland catchment using remote sensing, GIS and DC resistivity data: A case study from the Eastern Desert of Egypt

The coastal and alluvial areas of the Red Sea Mountains are mainly being developed for resorts and tourism activities. Given the development of occasional flash floods in the central part of the Red Sea area can be of destructive consequences to the various anthropogenic activities; thus the quantitative and qualitative assessments of the hydrological parameters and groundwater occurrence are presented. As a case study, Wadi Isl at the Red Sea coast has been hydrogeologically analyzed using an integrative approach of remote sensing, GIS and direct current resistivity (DCR) tools. The time area-zones have been estimated using and Manning's equation into the spatial analyses routines embedded within the ArcGIS. In this study, a synthetic effective rainfall of 10 mm has been applied to compute the spatially distributed runoff hydrograph. The estimated total runoff volume is approximately 8 million cubic meters, and the peak discharge rate is estimated to 163 cubic meters per second, which can be destructive to the main infrastructures in the flash flood pathways. Then, the 2D-electrical resistivity tomography (2D-ERT) surveys have been carried out at various localities along the main wadi course to explore the lateral and vertical variation of alluvium thickness and the saturated zones. Notably, the groundwater occurrence is contained in the structurally controlled graben. Therefore, the study has recommended the construction a main barrier at a natural deep gorge of the main outlet in order to fully control the flash floods and to enhance the potential recharge to the underlying alluvium aquifer. The present integrative approach of both surface and subsurface data is definitely needed to maximize the flash flood benefits.

Trust your peers! How trust among citizens can foster collective risk prevention

Reducing vulnerability to natural hazards is a shared responsibility of risk management authorities and populations, who are expected to implement safety precautions (e.g., securing furniture to wall studs in houses) and refrain from harmful behaviours (e.g., avoid parking in alluvial areas during flood alerts).In this paper we analyse resilience as a public good, where the individual interest (saving time and money, instead of investing in preventive measures) is often in conflict with that of the whole community (being prepared for potential crises). We hypothesize that, as in other real-life social dilemmas, trust among group members can encourage individual contributions to public safety, by counteracting the fear of other members’ defection. However, we also argue that the beneficial effects of trust on collective risk preparedness are conditional upon some key factors, namely, group stability and reputational pressures.We conducted three empirical studies to investigate subjects' decision-making dynamics about collective prevention in the face of risk from natural hazards. Our results suggest that trust in one's peers does increase willingness to contribute to collective risk preparedness (Study 1), and that this effect is based on expectations of direct reciprocity, thus requiring group stability to emerge (Study 2); moreover, the beneficial effect of trust is predicated on the presence of an external observer, whereas in the absence of reputational pressures willingness to invest in risk prevention decreases with trusted peers, thus indicating exploitation motives (Study 3). Taken together, these findings highlight a number of potential implications for participative risk prevention policies.

Microbial Organic Matter Utilization in High-Arctic Streams: Key Enzymatic Controls.

In the Arctic, climate changes contribute to enhanced mobilization of organic matter in streams. Microbial extracellular enzymes are important mediators of stream organic matter processing, but limited information is available on enzyme processes in this remote area. Here, we studied the variability of microbial extracellular enzyme activity in high-Arctic fluvial biofilms. We evaluated 12 stream reaches in Northeast Greenland draining areas exhibiting different geomorphological features with contrasting contents of soil organic matter to cover a wide range of environmental conditions. We determined stream nitrogen, phosphorus, and dissolved organic carbon concentrations, quantified algal biomass and bacterial density, and characterized the extracellular enzyme activities involved in catalyzing the cleavage of a range of organic matter compounds (e.g., β-glucosidase, phosphatase, β-xylosidase, cellobiohydrolase, and phenol oxidase). We found significant differences in microbial organic matter utilization among the study streams draining contrasting geomorphological features, indicating a strong coupling between terrestrial and stream ecosystems. Phosphatase and phenol oxidase activities were higher in solifluction areas than in alluvial areas. Besides dissolved organic carbon, nitrogen availability was the main driver controlling enzyme activities in the high-Arctic, which suggests enhanced organic matter mineralization at increased nutrient availability. Overall, our study provides novel information on the controls of organic matter usage by high-Arctic stream biofilms, which is of high relevance due to the predicted increase of nutrient availability in high-Arctic streams in global climate change scenarios.

Morphometry and longitudinal profile of the river cobras sub-basin in planning the location of underground dams

A study was carried out in the sub-basin of the River Cobras with the aim of evaluating the morphometric characteristics and longitudinal profile of the river basin as a tool for planning the location of underground dams. Morphometric parameters - compactness coefficient, form factor, drainage density and circularity index - were determined. An equilibrium profile was also performed in order to understand the dynamics of erosion and disposition in the sub-basin under study. The results showed that the River Cobras sub-basin is strongly elongated, with low drainage density and high rates of runoff in alluvial areas. The equilibrium profile indicated that the middle course (18 km, stretch 2) of the sub-basin includes a first-order anomaly and is susceptible to erosive processes along this stretch. The lower course (10 km, stretch 3) also has a first order anomaly; however, with a tendency to favour the aggregation of sedimentary material (larger sedimentary bundle) coming from the middle course. The middle course of the sub-basin has potential for the construction of submersible underground dams; whereas in the lower course, the construction of submerged underground dams is recommended. The physical morphometric parameters should not be analysed in isolation, but together with other aspects of surface- and groundwater quality, the recharge area and the social or production demand on the sub-basin.

A checklist of medically important flies (Order: Diptera) in the central region of Thailand

Chaiphongpachara T, Laojun S, Jongvisuttisan N, Tubsamut P, Dasom A. 2018. A checklist of medically important flies (Order: Diptera) in the central region of Thailand. Biodiversitas 19: 2134-2139. This study surveyed species of medically important flies in the central region of Thailand including Samut Songkram (coastal area representative), Bangkok (urban area representative), Phranakhon Si Ayutthaya (Lower alluvial area representative), Nakhon Sawan (upper alluvial area representative) and Sukhothai (mountainous area representative). This was done through a division of the central region into 5 areas, according to the landscape, including the coastal area, urban area, upper alluvial area, lower alluvial area and mountainous area. Flies were collected using insect nets and fly traps during July 2018. A total was 3872 adult flies, belonging to 4 subfamilies and 6 genera within 9 species were captured. The highest numbers of flies were found in the mountainous area, followed by coastal areas, upper alluvial area, urban area and lower alluvial area, respectively. All the study areas were within the central region of Thailand. The Chrysomya megacephala was the predominant species, with a total of 2953 adult flies captured. This was followed by the Musca domestica (n = 563), Achoetandrus rufifacies (n = 177) and Sacrophaga spp. (n = 137), respectively. The four species of flies collected in this study were Lucilia cuprina (n = 28), A. villeneuvi (n = 2), C. nigripes (n = 2) and Hemipygiopsis ligurriens (n = 2). The results of this study showed the distribution of flies, which is important information for diarrhoea vector control.

Chenopodium Seeds in Open-Air Archaeological Sites – How to Not Throw the Baby Out with the Bathwater

ABSTRACTDifferentiating between charred and uncharred plant remains may appear straightforward but for some taxa (here fat-hen, Chenopodium album type) can be very problematic. Recognition of the preservation state is obviously crucial for archaeobotanical data derived from dry, open-air sites. Fat-hen as a common weed, is also one of the most important components of a persistent soil seed bank. It is also a well-known food plant, gathered or cultivated. Numerous findings of fat-hen seeds in unclear states of preservation were noted in the Early Neolithic sites of the Linear Pottery culture in Kuyavia (N Europe). In previous studies such specimens were omitted as probably uncharred. Re-examination of Neolithic finds of fat-hen from that region showed the link of their abundancy with the earliest phases of the Neolithic occupation. The plant probably played an important role in the diet of the early Neolithic settlers there. It may indicate intensive use of local, open, fertile, probably alluvial areas. Distinguishing between ancient and modern specimens of that common weedy plant, producing large amounts of small, black, resistant seeds is thus very important, holding a great potential to shed new light on the origins of agricultural societies in this part of northern Europe.

Heterogeneity of a Tree Species Community in an Alluvial Area of Santa Catarina, Brazil

Heterogeneity of a Tree Species Community in an Alluvial Area of Santa Catarina, Brazil

Modeling cation exchange capacity in multi geochronological-derived alluvium soils: An approach based on soil depth intervals

Knowledge of soil chemical properties is indispensable to conduct sustainable land use management in alluvial areas. In this study we developed specific pedotransfer functions for cation exchange capacity (CEC-PTFs) in alluvial soils based on soil depth intervals. A soil data set (n = 1094 samples) at different depths from three different Nile River terraces (lower, middle, and upper) and the lower and upper Blue Nile terraces in Sudan was randomly collected and divided into a training data set (n1 = 900 samples) and a testing data set (n2 = 194 samples) for validation. Soil pH, texture, and organic matter were used as predictor variables to estimate CEC. PTF performance was evaluated with the coefficient of determination (R2), root mean square error (RMSE), and standard error for the estimate (SEE) between the observed and predicted values. Fourteen predictive equations were developed. Results revealed that the CEC of topsoil layers of the lower Nile River terrace were the most difficult to predict (r2 = 0.29 for training) while the deep soil layers (60–120 cm) of the Blue Nile terraces were predicted well (r2 = 0.99 for training). Sixty to 76% of CEC variation of the subsoil of the Nile River terraces could be explained by clay alone. From 85 to 90% of the CEC variation in the deep soils could be explained by organic matter, total silt, and total clay. Validated results indicate that the predictive models based on total clay were less reliable at predicting CEC in the top soil layers. Overall, the CEC-PTFs generated by multiple linear regression models (MLR) provided a reasonable estimate of CEC for most soils investigated.

Comparison of soil CO2 emissions between short-rotation coppice poplar stands and arable lands

Bioenergy crops are considered to have the potential for climate mitigation and socio-economic benefits owing to their capacity to sequester C and partially replace the consumption of fossil fuels. In this study, the effects on soil respiration of a recent conversion of arable land to high (H) and very high (VH) density short-rotation coppices (SRCs), as well as of agronomic treatments (fertilization with or without irrigation) and lane/row location, were investigated in an alluvial area in Italy. A survey of soil variability was carried out by collecting soil cores (0-60 cm depth) at 67 points to characterize surface and subsurface spatial distributions of pH, organic carbon, nitrogen and carbonates and identify comparable points for monitoring soil respiration. Soil CO2 emissions were monitored over the period April 2010-November 2011 at 27 locations covering the whole study site. The influence of land use (H-SRC, VH-SRC, corn and alfalfa) or treatments on soil respiration was evaluated considering both factors as fixed effects in a linear mixed model. Our results showed that (i) the high variability of soil properties even at small spatial scale has to be considered when selecting points for monitoring soil respiration in the field; (ii) the cumulative soil respiration over the study period at the VH-SRC was lower (1299 ± 30 g C m-2) than in croplands (1600 ±145 g C m-2) and higher along the rows than in the lanes; (iii) no significant differences in soil respiration were found between the H-SRC and corn field; (iv) two years after VH-SRC establishment, agronomic treatments did not appear to influence soil respiration; (v) land-use change affected the vertical soil organic carbon distribution and soil surface temperature, as reflected in soil respiration differences.

Holocene vegetation history of the Jeseníky Mts: Deepening elevational contrast in pollen assemblages since late prehistory

AbstractQuestionsHow did the vegetation of a Central European mountain region with a fragmented alpine zone develop during the Holocene? When did human land use start to alter summit grasslands? Which gradient in pollen assemblages was strongest and was it consistent through time?LocationJeseníky Mountains, Czech Republic.MethodsSixteen pollen records were subjected to DCA in order to explore patterns of compositional similarities in the fossil pollen data. Because only the last 6,000 years were recorded in the study sites from mountain summits, we restricted further analysis to this period. Twelve radiocarbon‐dated pollen records were subjected to DCCA constrained by modelled calibrated age. Responses of individual pollen types to the principal DCCA gradients were tested with GAMs.ResultsIn the DCA, Early Holocene samples were located close to recent ones due to abundant pollen of herbs, Poaceae, Betula, Pinus sylvestris type and rare pollen of climax deciduous trees. In the DCCA for the last 6,000 years, the sorting of sites along the first unconstrained axis correlated with altitude, which is a complex factor corresponding to temperature and geomorphology (flat summits vs alluvia of mountain rivulets). This elevational differentiation became more pronounced after 2,250 cal BP when summit peatlands started to contain more Vaccinium, Calluna vulgaris, Amaranthaceae, Plantago lanceolata and Rumex acetosa type pollen. In contrast, mid‐elevation pollen spectra started to contain more meadow herbs (Caltha, Potentilla type, Cirsium/Carduus). Picea pollen was surprisingly more associated with mid‐elevation than high‐elevation sites, unlike Fagus.ConclusionIncreasing contrast between summits and middle elevation alluvia seems to be a major feature of vegetation development over the last 6,000 years. While alluvial areas were encroached by Alnus–Picea forests, and later locally transformed into wet grasslands, grazing and forest burning at summits gradually increased abundance of acidophytic dwarf shrubs and peatlands, especially since the Iron Age. Human impact might facilitate beech expansion at high elevations, with Picea‐dominated forests being restricted to alluvia and around mid‐elevation basin peatlands prior to establishment of modern Picea plantations.

Probabilistic risk assessment of nitrate groundwater contamination from greenhouses in Albenga plain (Liguria, Italy) using lysimeters

The use of fertilizers in greenhouse-grown crops can pose a threat to groundwater quality and, consequently, to human beings and subterranean ecosystem, where intensive farming produces pollutants leaching. Albenga plain (Liguria, Italy) is an alluvial area of about 45km2 historically devoted to farming. Recently the crops have evolved to greenhouses horticulture and floriculture production. In the area high levels of nitrates in groundwater have been detected.Lysimeters with three types of reconstituted soils (loamy sand, sandy clay loam and sandy loam) collected from different areas of Albenga plain were used in this study to evaluate the leaching loss of nitrate (NO3−) over a period of 12weeks. Leaf lettuce (Lactuca sativa L.) was selected as a representative green-grown crop. Each of the soil samples was treated with a slow release fertilizer, simulating the real fertilizing strategy of the tillage. In order to estimate the potential risk for aquifers as well as for organisms exposed via pore water, nitrate concentrations in groundwater were evaluated by applying a simplified attenuation model to the experimental data. Results were refined and extended from comparison of single effects and exposure values (Tier I level) up to the evaluation of probabilistic distributions of exposure and related effects (Tier II, III IV levels).HHRA suggested HI >1 and about 20% probability of exceeding RfD for all the greenhouses, regardless of the soil. ERA suggested HQ>100 for all the greenhouses; 93% probability of PNEC exceedance for greenhouses containing sand clay loam. The probability of exceeding LC50 for 5% of the species was about 40% and the probability corresponding to DBQ of DEC/EC50>0.001 was >90% for all the greenhouses. The significantly high risk, related to the detected nitrate leaching loss, can be attributed to excessive and inappropriate fertigation strategies.

Proglacial sediment dynamics from daily to seasonal scales in a glaciated Alpine catchment (Bossons glacier, Mont Blanc massif, France)

AbstractThe sediment yields of Alpine catchments are commonly determined from streamload measurements made some distance downstream from glaciers. However, this approach indiscriminately integrates erosion processes occurring in both the glacial and proglacial areas. A specific method is required to ascertain the respective inputs from (i) subglacial and supraglacial sediments, (ii) proglacial hillslopes and (iii) proglacial alluvial areas or sandurs. This issue is addressed here by combining high‐resolution monitoring (2 min) of suspended sediment concentrations at different locations within a catchment with discharge gauging and precipitation data. This methodological framework is applied to two proglacial streams draining the Bossons glacier (Mont Blanc massif, France): the Bossons and Crosette streams. For the Bossons stream, discharge and suspended load data were acquired from June to October 2013 at 1.15 and 1.5 km from the glacial terminus, respectively upstream and downstream from a small valley sandur. These hydro‐sedimentary data are compared with the Crosette stream dataset acquired at the outlet of the Bossons glacier subglacial drainage system. A fourfold analysis focusing on seasonal changes in streamload and discharge, multilinear regression modelling, evaluation of the sandur flux balance and probabilistic uncertainty assessment is used to determine the catchment sediment budget and to explain the proglacial sediment dynamics. The seasonal fluctuation of the sediment signal observed is related to the gradual closing of the subglacial drainage network and to the role of the proglacial area in the sediment cascade: the proglacial hillslopes appear to be disconnected from the main channel and the valley sandur acts as a hydrodynamic sediment buffer both daily and seasonally. Our findings show that an understanding of proglacial sediment dynamics can help in evaluating paraglacial adjustment and subglacial erosion processes. Copyright © 2017 John Wiley & Sons, Ltd.

Evolution of the lower Guadalquivir river floodplain during the middle-late Holocene. Geoarchaeology and palaeogeographic reconstruction of the Italica Roman site (SW Spain)

Even before Italica was founded by the Romans at the end of the third century BC, this settlement maintained a close relationship with the morpho-dynamic evolution of the lower Guadalquivir river (SW Andalusia, Spain), especially with the lateral channel displacements. In order to reconstruct the palaeogeographic evolution of the alluvial area of Itálica during the second half of the Holocene, our research has focused on the study of the fluvial paleoforms and the alluvial soil-sedimentary sequence, with special emphasis on the analysis of the geoarchaeological records. Ancient maps and aerial photographs of various scales and diverse dates have been interpreted. Borehole cores and profiles, manually or mechanically opened, have also been done to obtain samples for laboratory tests of the representative floodplain soils and sediments. The chronologies provided by the archaeological record were completed with several radiocarbon dates. From these results we propose a possible solution at a local level to the traditional discussion about the existence and location of the ancient harbour of Italica; and for the alluvial plain as a whole, a double alternating palaeogeographic sequence trending to millennial-submillennial scale has been reached. The first one occurring controlled by hydrologic and climatic factors, modulated by a prolonged and extended human pressure on the basin, and showing a succession of four main stages characterized by the predominance of alluvial filling (4833-3206 cal BP; 3130-1989 cal BP; 1620 cal BP- XI century AD; and around the last 500 years), which are separated by periods of stability that favored alluvial soils formation; meanwhile, the second sequence presents short-time terms prone to riverbed design shifting (period prior to Late Bronze; Roman-republican era; central Middle Age), also separated by lengthy phases of morpho-hydrographic stability. In the latter case the main factor does not seem to be, as in the first of those, hydro-climatic shifts and land use changes, but rather the last small regional fluctuations of sea level that came with the second part of the Holocene.

A Low-Cost Indigenous Intervention which has Revolutionized the Drilling Technology and Changed the Life of Millions of Farmers in the State of Uttar Pradesh, India

An unknown indigenous driller combined the percussion and circulation drilling principles, resulting in the development of low cost, low weight manual boring set in the year 1990–1991/1991–1992, which revolutionized the shallow well drilling technology and made possible to drill about 4.5 million shallow bore wells in the State. This has changed the landscape of irrigated agriculture, changing the life of millions of small and marginal farmers and contributed a lot in increasing crop production and crop productivity. The developed drilling equipment locally known as “Pressure Boring Set” is manually operated, low cost and can be transported on bicycles. Drilling cost is also less. This low cost and simple technology made it possible to drill large number of shallow bore wells in comparatively short time span and less cost, consequently enhancing the rate of increase in irrigated area and in turn crop production and productivity. Cost of the boring set is also low, as compared to traditional sand pump hand boring set and suitable for alluvial areas.

The Isopach Mapping of Volcanic Deposits of Mount Samalas 1257 AD Based on the Values of Resistivity and Physical Properties

A detailed study had been conducted on the sediment of Mount Samalas’ volcanic eruption in 1257 AD. Using the framework of the reconstruction of the ancient eruption of Mount Samalas, the first step was to map and analyze the deposits of volcanic sediment. Secondly, we analyzed the effect of geomorphology and the distance function to the isopach thickness. The results show that a combination of methods allowed to provide a high resolution map of the distribution of the thickness of the volcanic deposits, both on the slope and in alluvial areas. Geo-electric survey results (both Vertical Electric Sound (VES) and 2D mapping) show consistent changes in the pattern of contrast resistivity layer interface, for all areas. The pattern changes in a row of the top layer, the high resistivity turned into the low. Furthermore, the second and third layer interface changes from low to the high resistivity. High resistivity on the top layer is interpreted as a layer of unconsolidated volcanic sediment. High resistivity values are range from 736 to 2000 Ohm.m on the top layer in the area of the slopes while in the area of alluvial, the resistivity values range from 20 to 958 Ohm.m. Generally, the volcanic deposits in the area of the slopes have a higher value of isopach (>17 m) than in areas of alluvial (<25 m). The geomorphology seemed to have no significant effect on the isopach value, particularly pyroclastic fallout. Such is the case with distance from the source to the site, which is not linear. The value of isopach increases westward from 21 to 31 km, in contrast to the East, which began to occur at a distance of 14 km to 21 km.