We need hydraulic fracturing in low permeability reservoirs to improve the inflow from the formation. Alternatively you drill a horizontal well. And even better you drill a horizontal well and make vertical fracs at regular intervals.
Not sure what you mean by relatibetween hydraulic fracturing and sinkholes. My immediate answer is no relationship.
The purpose of hydraulic fracturing to enhance the permeability of low permeable reservoir. it is mostly carried out in petroleum sector to withdraw hydrocarbons from low permeable rocks such as shales. Mostly, these reservoirs are located deep at about 5 km. if reservoirs are shallow then hydraulic fracturing may cause sinking problem