We consider a variant of a nonlinear parabolic system, proposed by Gilad, von Hardenberg, Provenzale, Shachak and Meron, in desertification studies, in which there is a strong absorption. The system models the mutual interaction between the biomass, the soil-water content w and the surface-water height which is diffused by means of the degenerate operator \(\Delta h^m\) with \(m\geq 2\). The main novelty in this article is that the absorption is given in terms of an exponent \(\alpha \in (0,1)$\) in contrast to the case \(\alpha =1\) considered in the previous literature. Thanks to this, some new qualitative behavior of the dynamics of the solutions can be justified.
After proving the existence of non-negative solutions for the system with Dirichlet and Neumann boundary conditions, we demonstrate the possible extinction in finite time and the finite speed of propagation for the surface-water height component \(h(t,x)\). Also, we prove, for the associate stationary problem, that if the precipitation datum \(p(x)\) grows near the boundary of the domain \(\partial \Omega \) as\(d(x,\partial \Omega )^{\frac{2\alpha }{m-\alpha }}\) then \(h^m(x)\) grows, at most, as \(d(x,\partial \Omega )^{\frac{2}{m-\alpha }}\). This property also implies the infinite waiting time property when the initial datum \(h_0(x)\) grows at fast as \(d(x,\partial S(h_0))^{\frac{2m}{m-\alpha }}\) near the boundary of its support \(S(h_0)\).
For more information see https://ejde.math.txstate.edu/Volumes/2021/08/abstr.html