Ts. Mirtskhulava Water Management Institute of Georgian Technical University THE FIELD STUDY OF THE COMBINE THREE TIER DRAINAGE Givi Gavardashvili Director of Institute, Doctor of Technical Sciences, Professor Maka Guguchia Ph Student Panevezys, Lithuania 2016

INTRODUCTION On the background on the climate change, aiming at efficiently cultivating the wet agricultural plots of field (with the area of ha) on Kolkheti Valley, Georgia (the maximum average annual amount of precipitations varies between 2100 and 2300 mm), an option of installing a field stand to study a Combine Three Tier Drainage (Georgian Patent Certificate No. GE P 2005, 3573 В) is considered [1,2].

2. IDENTIFYING THE DISTANCE BETWEEN THE DRAINS A design model given in Figure 1 was used for hydraulic calculations of the Combine Three Tier Drainage. Fig. 1. Design model of a Combine Three Tier Drainage

Where is the drainage length, is the proportionality factor, the same as the filtration coefficient (cm/sec); - is the depth of drainage installation (m) and is the form coefficient of the elliptic nod of the Combine Three Tier Drainage, which depends on the radius of curvature of the elliptic nod of the three tier perforated drainage (m). By knowing the ground water depth, as well as soil, hydrogeological and climatic conditions, the air and water regime of the agricultural crops can be regulated by using the Combine Three Tier Drainage. Figure 2 shows the design model to identify the distance between the drains. (l/sec) (1)

Figure 2 shows the design model to identify the distance between the drains. Fig. 2. Design model to identify the distance between the drains Let us simplify expression (1): We identify the distance between the drains (b) as follows: if the agricultural plots of field are cultivated by installing the Combine Three Tier Drainage system, then the distance between the drains is calculated with formula (3), but when it is necessary to install a combined drainage in the areas occupied by perennial plantations, the drainage system is installed in the middle of interrow, between the rows of perennial plantations. By means of calculations, it is also possible to install the drainage system with more than one drainage line in the interrow of the rows of perennial plantations[3]. (2) (3) (m)

3. FIELD STUDY OF THE COMBINE THREE TIER DRAINAGE Aiming at conducting the field experiments of the Combine Three Tier Drainage, a study polygon was organized on the experimental base of the Agrarian College of Georgian Technical University in village Didi Jikhaishi, Samtredia Region (See Fig. 3). Fig. 3. Field polygon in village Didi Jikhaishi

During the trench excavation, different layers of ground were identified, which were sampled and studied at the laboratory. The relevant graphs are given in Figure 4, and the average diameters are calculated with the following expression: Fig. 4. Grain-size curve – (21) soil depth – 0,30 m. (20) – soil depth – 0,50 m. (19) – soil depth – 1,0 m.

Let us calculate the mean diameter ( ) for each sample with the following formula: Where is the weight indicator of each fraction in the ground mass, and is the diameter of the sieves (mm). (4) Soil depth – 0,30 m. Soil depth – 0,50 m Soil depth – 1,0 m.

Figure 5 shows the full technological cycle to design the model of the Combine Three Tier Drainage.

During operation of the drainage system

Based on the field studies, the water intake capacity of the Combine Three Tier Drainage from the agricultural plots was calculated. Figures 6 and 7 show the graphs of the water discharge transported from the first and second drainage pipelines. Q 1 (l /sec) t 1 (sec) Fig. 5. Graph of dependence Q 1 = f(t 1 ) for the first drainage pipe Q 1 (l /sec) t 1 (sec) Fig. 6. Graph of dependence Q 2 = f(t 2 ) for the second drainage pipe

3. CONCLUSIONS Aiming at reaching efficient drying of wetlands on Kolkheti Valley, a new structure of the Combine Three Tier Drainage was developed. 2. The theoretical studies were used to fix the proper distance between the drains of the Combine Three Tier Drainage system. Based in the gained theoretical values, a field stand of a Combine Three Tier Drainage was installed in village Didi Jikhaishi, Samtredia Region, west Georgia. An integral curve of the grain size of the soil and ground fractions sampled from the field polygon is gained at the laboratory, and consequently, the mean diameter of the soil and ground is calculated. The water conductivity effect of two drains of the Combine Three Tier Drainage system is identified through the field studies.

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