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Coefficient of Discharge
for Double and Triple Cycle Labyrinth Weir
-- S M Yadav
A labyrinth spillway is an overflow weir folded in plan view to provide a longer total effective length for
a given overall spillway width. A labyrinth spillway has advantages compared to the straight overflow
weir and the standard ogee crest. The present paper proposes a mathematical model for a double and
triple cycle labyrinth weir based on experimental results. A concrete flume was constructed in the laboratory
and a double and triple cycle labyrinth weir with
25° labyrinth angle was installed. The design of
labyrinth weir installed in the concrete flume was carried out as per Tullis's guidelines. A mathematical model
for coefficient of discharge for labyrinth weir has been proposed using the experimental data.
© 2010 IUP. All Rights Reserved.
Sediment Yield Characteristics
of a Tropical River Basin
-- Chandramohan T and Balchand A N
This study was aimed at analyzing the sediment yield characteristics and its spatial and temporal
variation in the tropical river basin of Pamba river, which is one of the major rivers of the State of Kerala. The
daily discharge-sediment data pertaining to the Central Water Commission (CWC) gauging site for the
period 1986-2006 was used for the analyses. Annual, seasonal and monthly variations in discharge and
sediment load were analyzed using this data. In order to study the spatial variation in the sediment yield, three
more stations were identified within the river system on major tributaries for sediment monitoring. The
sediment contribution from each of these tributaries was also calculated. It was found that the water and
sediment transported by the river show a decreasing trend in recent years. The average annual discharge
and sediment load of the river are 3,838.6 MCM and 135,427 tons, respectively. The average sediment yield
for the river basin is estimated to be 79
tons/km2, which is very low compared to that of other major rivers
of India. The two monsoons, South-West (SW) and North-East (NE), contribute about
92% of the discharge and 96% of the sediment load. The influence of NE monsoon on sediment
production and delivery was also noticed. Hysteresis effect of discharge-sediment concentration relationship
was studied, and it was found that the majority of rainfall events produced a clockwise loop.
© 2010 IUP. All Rights Reserved.
Webpipa: A Decision Support System
for Rice Irrigation Water Management
-- Deepak T J, M s m Amin, Rashid Shariff and Rahman Ramli
In many countries, the Internet has become an element in people's daily life, offering new possibilities
for information access and sharing. In this new technological and information age, water is becoming a
source of conflict among domestic, industrial and agricultural users. Web-based Paddy Irrigation
Productivity Assessment (WebPIPA) is a platform for public participation in disputes and for evolving
decision-making processes in conflicting situations, especially in cases involving many stakeholders. WebPIPA is an
Internet-based model that is created to benefit the users in the water management sectors in order to make
timely decisions to increase Water Productivity Index (WPI), prevent water losses and increase crop
yield. Government and private agencies, researchers, station users, farmers, investors and buyers related to
this study area will be able to access the database through the Internet. While the development of WebPIPA
poses `human' and `technological' challenges, by strengthening the involvement of government
departments, the database can be used very effectively by all stakeholders at the same time, narrowing the digital
gap between the urban and rural communities.
© 2010 IUP. All Rights Reserved.
Non-Darcian Transmission of Water Properties
in Malaysian Peat Soil
-- Charles Bong Hin Joo and Ayob Katimon
Existing literature suggests that Darcy's law is not valid in layers of different degrees of decomposed
peat soil. The present study attempts to validate the applicability of Darcy's law by comparing the
velocity predicted by it and the velocity obtained through experiment for a peat soil column and also to assess
the changes of hydraulic conductivity, k, with the depth of peat soil layers. The suitability of Izbash's law
to predict the flow through peat soil column of different degrees of decomposition was tested by
determining the n value (Izbash's parameter). Izbash's law
(n = kin) is preferred because it is in continuity with
Darcy's law. Soil column studies were set up by applying different values in hydraulic gradient in order to
obtain discharge velocity, n , of the sample. From the experimental data, the suitable Izbash's parameter, n, for each depth of peat soil profile was determined. The result shows that Darcy's law is only appropriate for
the upper layer and as the layers become deeper, deviation from Darcy's law becomes larger. Izbash's
law provides a much better approximation of water flow through much deeper peat layers.
© 2010 IUP. All Rights Reserved.
Soil Characteristics and Maize Yield
as Affected by Soil Management Practices
in the Foothills of Shivaliks
-- M S Hadda, M Vashistha and Dapinder Pal Singh
Soil erosion is a serious menace and can adversely affect the soil characteristics and crop yield in
the foothills of Shivaliks. The present study was conducted at ZRSKA, Ballowal-Saunkhri, Nawanshar,
with the objective of studying the effect of soil management practices on some soil characteristics and yield
of maize crop. The profile properties showed an increase in bulk density, clay content and cation
exchange capacity by 4.2, 11.9 and 7.9%, respectively, in severely eroded A-horizon over the moderately eroded
A-horizon. In contrast, there is a tendency for a decrease in water holding capacity, silt content, organic
C content, available N and P by 6.2, 33.3, 5.2, 12.6 and 20.5%, respectively, in severely eroded A-horizon,
as compared to moderately eroded A-horizon. The different soil management practices , viz., contour
bunding and cultivation across the slope with recommended doses of inorganic fertilizers
(T2), cultivation of leveled land with application of recommended doses of inorganic fertilizers
(T3), and cultivation of leveled lands with application of recommended doses of inorganic fertilizers + farm yard manure (
T4) significantly improved the status of organic C, total N, available P, citric acid soluble P, CEC , Ca and Mg
contents, respectively, over the control
(T1) .
© 2010 IUP. All Rights Reserved.
Selenium Concentration in Fodder Crops
as Affected by the Application of Gypsum
and Phosphate Fertilizer
-- M J Singh, S K Dhillon and K S Dhillon
Field experiments were conducted to study the effect of gypsum and phosphate fertilizer on
selenium concentration in berseem (Trifolium
alexandrinum) and sorghum (Sorghum
bicolor) crops in the seleniferous region of Punjab. Sulphur was applied through gypsum at 0, 4, 8 and 12 q
ha_1 and phosphorus at 0, 60, 90 and 120 kg
P2O5 ha_1 through di-ammonium phosphate. Selenium concentration in berseem and
sorghum decreased significantly with the application of 8 and 12 q gypsum
ha_1. In different cuts of berseem, the decrease in Se concentration varied from 39% to 49% with the application of 12 q gypsum
ha_1. The effectiveness of gypsum decreased, as the growth of berseem advanced towards maturity.
No consistent changes in Se concentration of fodder crops were observed with the application of
phosphate fertilizer. The results suggest that gypsum application to seleniferous soils may be an economically
viable option for reducing Se accumulation by forage crops. However, there is a need to further verify the role of
P in regulating Se uptake by different crops.
© 2010 IUP. All Rights Reserved.
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May '10
