STOCHASTIC MODELING OF POOL-TO-POOL STRUCTURE IN SMALL NEVADA RANGELAND STREAMS

We developed, calibrated, and verified a compound Poisson process mode l of pool-to-pool spacing and size using an exponential distribution f or spacing and gamma distributions for length and width on 12 rangelan d streams in Nevada. Neither distribution parameter varied with simple stream morphologic or vegetation characteristics. We verified the mod el by comparing the first three moments and distributions of stream si mulations with observed streams using two transect-based sampling sche mes. Very small errors stemmed from an inability to reproduce autocorr elation of width at short distances, pool cyclicity, and additional de nsity at the tails. We conclude that the presented model is accurate f or small, Nevada, rangeland streams and for pools located randomly on small streams with forced pool-riffle or step-pool sequences and regul arly on larger, pool-riffle systems. Simulated streams may be used for testing stream survey procedures and hypotheses regarding pool habita t, spacing, and length.