Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Rain water transport and storage in a model sandy soil with hydrogel
  particle additives   We study rain water infiltration and drainage in a dry model sandy soil with
superabsorbent hydrogel particle additives by measuring the mass of retained
water for non-ponding rainfall using a self-built 3D laboratory set-up. In the
pure model sandy soil, the retained water curve measurements indicate that
instead of a stable horizontal wetting front that grows downward uniformly, a
narrow fingered flow forms under the top layer of water-saturated soil. This
rain water channelization phenomenon not only further reduces the available
rain water in the plant root zone, but also affects the efficiency of soil
additives, such as superabsorbent hydrogel particles. Our studies show that the
shape of the retained water curve for a soil packing with hydrogel particle
additives strongly depends on the location and the concentration of the
hydrogel particles in the model sandy soil. By carefully choosing the particle
size and distribution methods, we may use the swollen hydrogel particles to
modify the soil pore structure, to clog or extend the water channels in sandy
soils, or to build water reservoirs in the plant root zone.

10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
12
The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
3
The categories of this paper are: physics
28
The categories of this paper are: alg-geom
34
The categories of this paper are: chem-ph
6
The categories of this paper are: astro-ph
23
The categories of this paper are: solv-int
27
The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th