Crop production in arid and semi-arid environments is strongly affected by temporal variation of water availability during the growth period. In-situ water harvesting techniques such as tied ridges and mulching improve water availability over time and may improve crop yield. A field experiment was conducted in 2013 and 2014 in the Gule sub-watershed, Northern Ethiopia to study the effect of combining in-situ water harvesting techniques on on-site water regime, i.e., runoff and soil-moisture content. Five treatments with tied ridges, straw mulch, tied ridges and straw mulch together, straw mulch plus effective microorganisms and a combination of tied ridges, straw mulch and effective microorganisms and an untreated control were tested. Combined tied ridges and straw mulch with and without effective microorganisms significantly reduced average runoff per event by 78 and 88%, respectively, compared to the control. Tied ridges alone reduced runoff by 56% and straw mulch with and without effective microorganisms reduced runoff by 49 and 53%, respectively. Average soil-moisture content over the two years was significantly higher (22.4%) in combined tied ridges and straw mulch than the control (19.9%). Tied ridges or straw mulch alone significantly reduced runoff and improved soil-moisture content, but the two combined were more efficient. The findings suggest that combining straw mulch and tied ridges enhance water infiltration into the soil and improve water availability during the growing season, thereby protecting crops from dry periods.