This paper presents the results of the construction of an improvised double and single ring infiltrometers. The study was carried in Auchi Polytechnic campus, after the construction, the double ring and single ring infiltrometer were used to carryout infiltration tests at four different locations.

Infiltration is the process of water movement from the ground surface into the soil and is an important component in the hydrological cycle. Infiltration characteristics of soils can be quantified by direct measurement on the field and/or when field infiltration data are fitted mathematically to infiltration models. Lili et al. reviewed the commonly used direct methods for measuring soil infiltration which include: single ring and double ring infiltrometers, mariotte-double ring infiltrometer, disc permeameter, rainfall simulator, runoff-on-ponding, runoff-on-out and linear source methods, the results obtained from field infiltration test and soil analysis are used for infiltration modeling.

The general knowledge of the infiltration rate of soils has been obtained for many field conditions in the past, and results applied in many field works, there is dearth of information on the infiltration characteristics of soils within Auchi Polytechnic campus which would have aided engineers in hydrologic/hydraulic design of water disposal structures, soil management and erosion control works et cetera. The knowledge of the infiltration capacity of soils within Auchi Polytechnic campus will be very helpful in carrying out soil related research works, infrastructural works and other works involving erosion control and management.

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Inhalt

1. INTRODUCTION

2. MATERIALS AND METHODS
2.1. Study Area
2.2 Construction Criteria
2.3 testing and Evaluation
2.4 Estimation of Model Parameters
2.5 Statistical Analysis and Model Validation

3. RESULT AND DISCUSSION
3.1 Soil Properties
3.2 Field Measured Infiltration
3.3 Comparison of the cumulative infiltration by the Single and Double ring Infiltrometers
3.4 Model’s Parameter Evaluation
3.5 Simulation of Cumulative Infiltration using the Estimated Parameters
3.6 Model Validation

4. CONCLUSION

REFERENCES

ABSTRACT

Key Words: Single and Double ring infiltrometer, infiltration models, Kostiakov,

1. INTRODUCTION

Infiltration is the process of water movement from the ground surface into the soil and is an important component in the hydrological cycle (Haghiabi et. al., 2011). Infiltration characteristics of soils can be quantified by direct measurement on the field and/or when field infiltration data are fitted mathematically to infiltration models (Oku and Aiyelari, 2011). Lili et al., (2008) reviewed the commonly used direct methods for measuring soil infiltration which include: single ring and double ring infiltrometers, mariotte-double ring infiltrometer, disc permeameter, rainfall simulator, runoff-on-ponding, runoff-on-out and linear source methods, the results obtained from field infiltration test and soil analysis are used for infiltration modeling.

The general knowledge of the infiltration rate of soils has been obtained for many field conditions in the past, and results applied in many field works, there is dearth of information on the infiltration characteristics of soils within Auchi Polytechnic campus which would have aided engineers in hydrologic/hydraulic design of water disposal structures, soil management and erosion control works et cetera. The knowledge of the infiltration capacity of soils within Auchi Polytechnic campus will be very helpful in carrying out soil related research works, infrastructural works and other works involving erosion control and management. This paper presents the results of the construction of an improvised double and single ring infiltrometers, carry out a comparative study of the variability of the cumulative infiltration depths of the single and double ring infiltrometers and also evaluate the ability of two infiltration models (Kostiakov’s, and Philip’s model) to predict cumulative infiltration for the five locations in comparison with the field obtained data.

2. MATERIALS AND METHODS

2.1. Study Area

This study was be carried out in specific locations within Auchi Polytechnic campus, Auchi Polytechnic is located between latitude 70 10’ and 70 20’ north of the equator and longitude 60 16’ and 60 36’ east of the Greenwich Meridian with an altitude of 207m. The locations chosen for infiltration runs are Agricultural & Bio-Environmental Engineering experimental field behind the workshop, School of ICT, School of Environmental studies, and Campus II, which were denoted by A, B, C and D respectively.

2.2 Construction Criteria

The development of an improvised double ring and single ring infiltrometer was constructed based on standard principles . This system involved the use of sheet metal of 2 mm thickness, this was chosen to avoid bending and so it can withstand the impact of the blow from the mallet while it is been driven into the soil. The outer ring of 50cm diameter and 40cm height with inner and single ring 30cm diameter and 40 cm height was constructed from the sheet metal. The meter rule, mallet, and other accompanying materials were purchased directly from the market.

2.3 testing and Evaluation

After the construction, the double ring and single ring infiltrometer were used to carryout infiltration tests at four different locations. Undisturbed samples were also taken from each location at depth of 0 – 15cm and 15 - 30cm using core samplers to determine the soil’s physical property of the study areas. Both rings were hammered 15 cm into the soil with a plank to protect the surface of the ring from damage during hammering. The test started by pouring water into the inner ring to an appropriate depth and at the same time, adding water to the space between the two rings to the same depth as quickly as possible. The time when the test began was recorded and the water level on the measuring rod was noted. After two (2) minutes, the drop in water level in the inner ring was recorded on the measuring rod and water added to bring the level back to approximately the original level at the start of the test. The water level outside the ring was maintained similar to the one inside. Each infiltration test lasted for about four (4) hours, the cumulative time intervals will be; 2, 4, 7, 10, 15, 20, 30, 45, 60, 80, 100, 120, 150, 180, 210 and 240 minutes. The cumulative infiltration depth at the elapsed time was being recorded accordingly.

2.4 Estimation of Model Parameters

In order to assess the performance of the selected models in predicting the cumulative infiltration, the parameters of each model were first determined as follows: