water Article Simulating Rainfall Interception by Caatinga Vegetation Using the Gash Model Parametrized on Daily and Seasonal Bases Daniela C. Lopes 1, * , Antonio José Steidle Neto 1 , Thieres G. F. Silva 2 , Luciana S. B. Souza 2 ,Sérgio Zolnier 3 and Carlos A. A. Souza 2   Citation: Lopes, D.C.; Steidle Neto, A.J.; Silva, T.G.F.; Souza, L.S.B.; Zolnier, S.; Souza, C.A.A. Simulating Rainfall Interception by Caatinga Vegetation Using the Gash Model Parametrized on Daily and Seasonal Bases. Water 2021, 13, 2494. https:// doi.org/10.3390/w13182494 Academic Editors: Tamara Tokarczyk and Andrzej Walega Received: 16 August 2021 Accepted: 9 September 2021 Published: 11 September 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Campus Sete Lagoas, Federal University of São João del-Rei, Rodovia MG 424, Km 47, Sete Lagoas 35701-970, Minas Gerais, Brazil; antonio@ufsj.edu.br 2 Academic Unit of Serra Talhada, Federal Rural University of Pernambuco, Serra Talhada 56900-000, Pernambuco, Brazil; thieres.silva@ufrpe.br (T.G.F.S.); luciana.sandra@ufrpe.br (L.S.B.S.); carlosandre08_@msn.com (C.A.A.S.) 3 Department of Agricultural Engineering, Federal University of Viçosa, Av. Peter Henry Rolfs, s/n, Viçosa 36570-000, Minas Gerais, Brazil; zolnier@ufv.br * Correspondence: danielalopes@ufsj.edu.br; Tel.: +55-31-3775-5521 Abstract: Rainfall partitioning by trees is an important hydrological process in the contexts of water resource management and climate change. It becomes even more complex where vegetation is sparse and in vulnerable natural systems, such as the Caatinga domain. Rainfall interception modelling allows extrapolating experimental results both in time and space, helping to better understand this hydrological process and contributing as a prediction tool for forest managers. In this work, the Gash model was applied in two ways of parameterization. One was the parameterization on a daily basis and another on a seasonal basis. They were validated, improving the description of rainfall partitioning by tree species of Caatinga dry tropical forest already reported in the scientific literature and allowing a detailed evaluation of the influence of rainfall depth and event intensity on rainfall partitioning associated with these species. Very small (0.0–5.0 mm) and low-intensity (0–2.5 mm h −1 ) events were significantly more frequent during the dry season. Both model approaches resulted in good predictions, with absence of constant and systematic errors during simulations. The sparse Gash model parametrized on a daily basis performed slightly better, reaching maximum cumulative mean error of 9.8%, while, for the seasonal parametrization, this value was 11.5%. Seasonal model predictions were also the most sensitive to canopy and climatic parameters. Keywords: rainfall partitioning; dry tropical forest; gash model; interception modelling 1. Introduction Water availability is limited in arid and semiarid regions, with rainfall interception playing an important role on site and catchment water balances, as well as in the context of climate change [1]. Rainfall partitioning by trees is an intricate process, mainly affected by canopy and weather factors, such as the characteristics of rainfall events, becoming even more complex where vegetation is sparse [2]. Thus, rainfall interception modelling appears as an important tool for extrapolating experimental results both in time and space, helping to better understand this hydrological process, as well as to implement effective water resource management and land use planning. Many mathematical models have been developed, validated and successfully ap- plied to simulate rainfall partitioning in different forest types, including coniferous and hardwood stands [3–5], rainforests [6,7], deciduous and sparse canopies [8–10], mixed stands [11] and crops [12]. However, there are few studies about simulating or evaluating the rainfall interception in Caatinga vegetation [1,13–16]. This domain corresponds to an area of tropical dry forest with deciduous tree-shrubs, which covers close to one million km 2 in the Northeast of Brazil, occupying around 50% of this region [17]. Caatinga is Water 2021, 13, 2494. https://doi.org/10.3390/w13182494 https://www.mdpi.com/journal/water