The influence of the opening width of check dams on bedload continuity of mountain rivers

Artificial recharge plays a prominent role in the sustainable management of groundwater resources. The study has proposed a methodology to viable artificial recharge structure using geographical information system (GIS) and empirical equation techniques for augmenting groundwater resources in the Ranchi urban and rural area of Ranchi District, Jharkhand. The thematic layers for geomorphology, drainage density, order of streams, runoff and trend has been prepared in the GIS environment using convection and remote sensing data. It has been found that the slope and topographic gradient of Ranchi region is one of the major governing factors, which restricts to hold surface water stagnant. Jumar watershed is found as the most feasible watershed for the construction of check dams/percolation tanks followed by Lower Subarnarekha watershed. Out of 15 deeper exploratory wells, 14 are declining. Harmu watershed is found to be in the worst condition in terms of availability of runoff water. Harmu, Kanke, Bariyatu, Namkum, Doranda, Hinoo and Hatia have found as the most suitable locations for installation of RTRWH within the Ranchi urban area. Based on the available field information, check dams are suggested as the most promising artificial recharge structures for Ranchi rural environment.

Download Full-text

Large-Scale Application of Biofiltration Swale Runoff Management Practices

Water Practice & Technology ◽

10.2166/wpt.2007.049 ◽

2007 ◽

Vol 2 (2) ◽

Author(s):

William C. Lucas

Keyword(s):

Large Scale ◽

Management Practices ◽

Peak Flow ◽

Low Impact Development ◽

Urban Runoff ◽

Management Model ◽

Check Dams ◽

Runoff Reduction ◽

Impervious Area ◽

Hydrologic Responses

Retaining rainfall where it lands is a fundamental benefit of Low Impact Development (LID). The Delaware Urban Runoff Management Model (DURMM) was developed to address the benefits of LID design. DURMM explicitly addresses the benefits of impervious area disconnection as well as swale flow routing that responds to flow retardance changes. Biofiltration swales are an effective LID BMP for treating urban runoff. By adding check dams, the detention storage provided can also reduce peak rates. This presentation explores how the DURMM runoff reduction approach can be integrated with detention routing procedures to project runoff volume and peak flow reductions provided by BMP facilities. This approach has been applied to a 1,200 unit project on 360 hectares located in Delaware, USA. Over 5 km of biofiltration swales have been designed, many of which have stone check dams placed every 30 to 35 meters to provide detention storage. The engineering involved in the design of such facilities uses hydrologic modeling based upon TR-20 routines, as adapted by the DURMM model. The hydraulic approach includes routing of flows through the check dams. This presentation summarizes the hydrological network, presents the hydrologic responses, along with selected hydrographs to demonstrate the potential of design approach.

Download Full-text

Geoinformation Mapping Through the Types of Geological and Geomorphological Structure of the Katun Valley (Altay Mountains) Based on Morphometric Indicators

Geodesy and Cartography ◽

10.22389/0016-7126-2018-938-8-38-43 ◽

2018 ◽

Vol 938 (8) ◽

pp. 38-43

Author(s):

S.A. Kotler ◽

I.D. Zolnikov ◽

D.V. Pchelnikov

Keyword(s):

Morphometric Parameters ◽

Morphometric Parameter ◽

Geological History ◽

Mountain Rivers ◽

Quaternary Period ◽

Modern Variety ◽

Altay Mountains ◽

History Of

The types of geological and geomorphological structure of the Katun valley are distinguished in the work. For this, a method of geoinformation mapping using morphometric indicators of the valley’s width and meandering of the channel was developed. The morphometric parameter of the valley’s width was calculated as the total area of terraces. As the morphometric parameters of the channel’s meandering, the angles of the river segments’ deviation relative to each other were calculated. Conjugated analysis of these morphometric indicators enabled identifying 18 morphotypes. These morphotypes according to the geological and geomorphological structure of the valley were combined into 4 classes. Separation of the Katun valley in certain classes and morphotypes is due to the different geological history of these sites during the Quaternary period. The most important reasons predetermining the modern variety of geological and geomorphological types of the valley are neotectonic movements and exogenous phenomena (glaciers, dam lakes, landslides, etc.) naturally localized in the space from the upstream of the river to its exit into the foothills. The developed method can be applied for quantitative morphometric classification of the mountain rivers’ valleys in other regions.

Download Full-text

Design of Grating Al2O3 Passivation Structure Optimized for High-Efficiency Cu(In,Ga)Se2 Solar Cells

Sensors ◽

10.3390/s21144849 ◽

2021 ◽

Vol 21 (14) ◽

pp. 4849

Author(s):

Chan Hyeon Park ◽

Jun Yong Kim ◽

Shi-Joon Sung ◽

Dae-Hwan Kim ◽

Yun Seon Do

Keyword(s):

Solar Cells ◽

High Efficiency ◽

Surface Passivation ◽

Rear Surface ◽

Maximum Efficiency ◽

Structural Factors ◽

Carrier Recombination ◽

Cigs Solar Cells ◽

Effective Carrier ◽

Opening Width

In this paper, we propose an optimized structure of thin Cu(In,Ga)Se2 (CIGS) solar cells with a grating aluminum oxide (Al2O3) passivation layer (GAPL) providing nano-sized contact openings in order to improve power conversion efficiency using optoelectrical simulations. Al2O3 is used as a rear surface passivation material to reduce carrier recombination and improve reflectivity at a rear surface for high efficiency in thin CIGS solar cells. To realize high efficiency for thin CIGS solar cells, the optimized structure was designed by manipulating two structural factors: the contact opening width (COW) and the pitch of the GAPL. Compared with an unpassivated thin CIGS solar cell, the efficiency was improved up to 20.38% when the pitch of the GAPL was 7.5–12.5 μm. Furthermore, the efficiency was improved as the COW of the GAPL was decreased. The maximum efficiency value occurred when the COW was 100 nm because of the effective carrier recombination inhibition and high reflectivity of the Al2O3 insulator passivation with local contacts. These results indicate that the designed structure has optimized structural points for high-efficiency thin CIGS solar cells. Therefore, the photovoltaic (PV) generator and sensor designers can achieve the higher performance of photosensitive thin CIGS solar cells by considering these results.

Download Full-text